Black Hole Phase Transition in Massive Gravity
NASA Astrophysics Data System (ADS)
Ning, Shou-Li; Liu, Wen-Biao
2016-07-01
In massive gravity, some new phenomena of black hole phase transition are found. There are more than one critical points under appropriate parameter values and the Gibbs free energy near critical points also has some new properties. Moreover, the Maxwell equal area rule is also investigated and the coexistence curve of the black hole is given.
Black Hole Interior in Quantum Gravity.
Nomura, Yasunori; Sanches, Fabio; Weinberg, Sean J
2015-05-22
We discuss the interior of a black hole in quantum gravity, in which black holes form and evaporate unitarily. The interior spacetime appears in the sense of complementarity because of special features revealed by the microscopic degrees of freedom when viewed from a semiclassical standpoint. The relation between quantum mechanics and the equivalence principle is subtle, but they are still consistent. PMID:26047218
Black hole thermodynamics in MOdified Gravity (MOG)
NASA Astrophysics Data System (ADS)
Mureika, Jonas R.; Moffat, John W.; Faizal, Mir
2016-06-01
We analyze the thermodynamical properties of black holes in a modified theory of gravity, which was initially proposed to obtain correct dynamics of galaxies and galaxy clusters without dark matter. The thermodynamics of non-rotating and rotating black hole solutions resembles similar solutions in Einstein-Maxwell theory with the electric charge being replaced by a new mass dependent gravitational charge Q =√{ αGN } M. This new mass dependent charge modifies the effective Newtonian constant from GN to G =GN (1 + α), and this in turn critically affects the thermodynamics of the black holes. We also investigate the thermodynamics of regular solutions, and explore the limiting case when no horizons forms. So, it is possible that the modified gravity can lead to the absence of black hole horizons in our universe. Finally, we analyze corrections to the thermodynamics of a non-rotating black hole and obtain the usual logarithmic correction term.
Black holes in pure Lovelock gravities
Cai Ronggen; Ohta, Nobuyoshi
2006-09-15
Lovelock gravity is a fascinating extension of general relativity, whose action consists of dimensionally extended Euler densities. Compared to other higher order derivative gravity theories, Lovelock gravity is attractive since it has a lot of remarkable features such as the fact that there are no more than second order derivatives with respect to the metric in its equations of motion, and that the theory is free of ghosts. Recently, in the study of black strings and black branes in Lovelock gravity, a special class of Lovelock gravity is considered, which is named pure Lovelock gravity, where only one Euler density term exists. In this paper we study black hole solutions in the special class of Lovelock gravity and associated thermodynamic properties. Some interesting features are found, which are quite different from the corresponding ones in general relativity.
Charged dilatonic black holes in gravity's rainbow
NASA Astrophysics Data System (ADS)
Hendi, S. H.; Faizal, Mir; Panah, B. Eslam; Panahiyan, S.
2016-05-01
In this paper, we present charged dilatonic black holes in gravity's rainbow. We study the geometric and thermodynamic properties of black hole solutions. We also investigate the effects of rainbow functions on different thermodynamic quantities for these charged black holes in dilatonic gravity's rainbow. Then we demonstrate that the first law of thermodynamics is valid for these solutions. After that, we investigate thermal stability of the solutions using the canonical ensemble and analyze the effects of different rainbow functions on the thermal stability. In addition, we present some arguments regarding the bound and phase transition points in context of geometrical thermodynamics. We also study the phase transition in extended phase space in which the cosmological constant is treated as the thermodynamic pressure. Finally, we use another approach to calculate and demonstrate that the obtained critical points in extended phase space represent a second order phase transition for these black holes.
Gravity, black holes, and the universe
Nicolson, I.
1981-01-01
The book treats current understandings of the nature and properties of gravity, with particular emphasis on its role in the physics of black holes and the structure and evolution of the universe as a whole. The development of modern ideas on force, motion and gravity is traced from the systems of Aristotle and Ptolemy through the work of Copernicus, Galileo and Kepler to Newton's law of universal gravitation and Einstein's general theory of relativity. Particular attention is then given to the role of gravity in stellar motions and to the phenomena determined by the immense gravitational forces associated with bodies of such great density, including relativistic effects, tidal forces, space-time effects, event horizons, rotation, mass and electrical charge, the existence of naked singularities and white holes, and black-hole thermodynamics. The existence of actual black holes in the universe is considered, and various black-hole candidates in the Galaxy, quasars and galactic nuclei are indicated. The role of gravity in cosmology is then examined, with attention given to the implications of general relativity, the Hubble law, the age of the universe, the density of the universe and its eventual fate. Possible alternative to general relativity as a theory of gravitation are considered, including theories of variable gravitational constant, grand unified theories, and quantum gravity.
Black holes in higher derivative gravity.
Lü, H; Perkins, A; Pope, C N; Stelle, K S
2015-05-01
Extensions of Einstein gravity with higher-order derivative terms arise in string theory and other effective theories, as well as being of interest in their own right. In this Letter we study static black-hole solutions in the example of Einstein gravity with additional quadratic curvature terms. A Lichnerowicz-type theorem simplifies the analysis by establishing that they must have vanishing Ricci scalar curvature. By numerical methods we then demonstrate the existence of further black-hole solutions over and above the Schwarzschild solution. We discuss some of their thermodynamic properties, and show that they obey the first law of thermodynamics. PMID:25978224
Gravity coupling from micro-black holes
NASA Astrophysics Data System (ADS)
Scardigli, Fabio
2000-06-01
Recently much work has been done in lowering the Planck threshold of quantum gravitational effects (submillimeter dimension(s), Horava-Witten fifth dimension, strings or branes low energy effects, etc.). Working in the framework of 4-dim gravity, with semi-classical considerations based on Hawking evaporation of planckian micro-black holes, I shall show here as quantum gravity effects could occur also near GUT energies.
Astrophysical black holes in screened modified gravity
Davis, Anne-Christine; Jha, Rahul; Muir, Jessica; Gregory, Ruth E-mail: r.a.w.gregory@durham.ac.uk E-mail: jlmuir@umich.edu
2014-08-01
Chameleon, environmentally dependent dilaton, and symmetron gravity are three models of modified gravity in which the effects of the additional scalar degree of freedom are screened in dense environments. They have been extensively studied in laboratory, cosmological, and astrophysical contexts. In this paper, we present a preliminary investigation into whether additional constraints can be provided by studying these scalar fields around black holes. By looking at the properties of a static, spherically symmetric black hole, we find that the presence of a non-uniform matter distribution induces a non-constant scalar profile in chameleon and dilaton, but not necessarily symmetron gravity. An order of magnitude estimate shows that the effects of these profiles on in-falling test particles will be sub-leading compared to gravitational waves and hence observationally challenging to detect.
Light, Gravity and Black Holes
ERIC Educational Resources Information Center
Falla, David
2012-01-01
The nature of light and how it is affected by gravity is discussed. Einstein's prediction of the deflection of light as it passes near the Sun was verified by observations made during the solar eclipse of 1919. Another prediction was that of gravitational redshift, which occurs when light emitted by a star loses energy in the gravitational field…
Charged black holes in generalized teleparallel gravity
Rodrigues, M.E.; Houndjo, M.J.S.; Tossa, J.; Momeni, D.; Myrzakulov, R. E-mail: sthoundjo@yahoo.fr E-mail: d.momeni@yahoo.com
2013-11-01
In this paper we investigate charged static black holes in 4D for generalized teleparallel models of gravity, based on torsion as the geometric object for describing gravity according to the equivalence principle. As a motivated idea, we introduce a set of non-diagonal tetrads and derive the full system of non linear differential equations. We prove that the common Schwarzschild gauge is applicable only when we study linear f(T) case. We reobtain the Reissner-Nordstrom-de Sitter (or RN-AdS) solution for the linear case of f(T) and perform a parametric cosmological reconstruction for two nonlinear models. We also study in detail a type of the no-go theorem in the framework of this modified teleparallel gravity.
Asymptotically charged BTZ black holes in gravity's rainbow
NASA Astrophysics Data System (ADS)
Hendi, S. H.
2016-04-01
Motivated by the wide applications of BTZ black holes and interesting results of gravity's rainbow, we consider three dimensional rainbow solutions and investigate their thermodynamic properties. In addition to investigate black holes thermodynamics related to AdS/CFT correspondence, one may regard gravity's rainbow to encode quantum gravity effects into the black hole solutions. We take into account the various models of linear and nonlinear electrodynamics and study their effects on the gravity's rainbow spacetime. We also examine thermal stability and find that obtained three dimensional rainbow black holes are thermally stable.
Exact teleparallel gravity of binary black holes
NASA Astrophysics Data System (ADS)
El Hanafy, W.; Nashed, G. G. L.
2016-02-01
An exact solution of two singularities in the teleparallel equivalent to general relativity theory has been obtained. A holographic visualization of the binary black holes (BBHs) space-time, due to the non vanishing torsion scalar field, has been given. The acceleration tensor of BBHs space-time has been calculated. The results identify the repulsive gravity zones of the BBHs field. The total conserved quantities of the BBHs has been evaluated. Possible gravitational radiation emission by the system has been calculated without assuming a weak field initial data.
Black holes in Born-Infeld extended new massive gravity
Ghodsi, Ahmad; Yekta, Davood Mahdavian
2011-05-15
In this paper we find different types of black holes for the Born-Infeld extended new massive gravity. Our solutions include (un)charged warped (anti-)de Sitter black holes for four and six derivative expanded action. We also look at the black holes in unexpanded Born-Infeld action. In each case we calculate the entropy, angular momentum and mass of the black holes. We also find the central charges for the conformal field theory duals.
Geometrothermodynamics of black holes in Lorentz noninvariant massive gravity
NASA Astrophysics Data System (ADS)
Sánchez, Alberto
2016-07-01
We analyze a static and spherically symmetric hairy black hole solution in noninvariant massive gravity. The formalism of geometrothermodynamics is used to describe the thermodynamic characteristics of this black hole in a Legendre invariant way. For a black hole in massive gravity, the geometry of the space of equilibrium states is computed showing that it contains information about the thermodynamic interaction, critical points, and phase transitions structure.
Quantum-gravity fluctuations and the black-hole temperature
NASA Astrophysics Data System (ADS)
Hod, Shahar
2015-05-01
Bekenstein has put forward the idea that, in a quantum theory of gravity, a black hole should have a discrete energy spectrum with concomitant discrete line emission. The quantized black-hole radiation spectrum is expected to be very different from Hawking's semi-classical prediction of a thermal black-hole radiation spectrum. One naturally wonders: Is it possible to reconcile the discrete quantum spectrum suggested by Bekenstein with the continuous semi-classical spectrum suggested by Hawking? In order to address this fundamental question, in this essay we shall consider the zero-point quantum-gravity fluctuations of the black-hole spacetime. In a quantum theory of gravity, these spacetime fluctuations are closely related to the characteristic gravitational resonances of the corresponding black-hole spacetime. Assuming that the energy of the black-hole radiation stems from these zero-point quantum-gravity fluctuations of the black-hole spacetime, we derive the effective temperature of the quantized black-hole radiation spectrum. Remarkably, it is shown that this characteristic temperature of the discrete (quantized) black-hole radiation agrees with the well-known Hawking temperature of the continuous (semi-classical) black-hole spectrum.
Black hole remnant from gravity's rainbow
NASA Astrophysics Data System (ADS)
Farag Ali, Ahmed
2014-05-01
In this work, we investigate black hole (BH) physics in the context of the gravity rainbow. We investigate this through rainbow functions that have been proposed by Amelino-Camelia [Living Rev. Relativity 16, 5 (2013)] and Amelino-Camelia et al. in [Int. J. Mod. Phys. A 12, 607 (1997)]. This modification will give corrections to both the temperature and the entropy of BHs, and hence it changes the picture of Hawking radiation greatly when the size of the BH approaches the Planck scale. It prevents the BH from total evaporation, predicting the existence of a BH remnant, which may resolve the catastrophic behavior of Hawking radiation as the BH mass approaches zero.
Black holes in Gauss-Bonnet gravity's rainbow
NASA Astrophysics Data System (ADS)
Hendi, Seyed Hossein; Faizal, Mir
2015-08-01
In this paper, we will generalize the Gauss-Bonnet gravity to an energy-dependent Gauss-Bonnet theory of gravity, which we shall call the Gauss-Bonnet gravity's rainbow. We will also couple this theory to a Maxwell's theory. We will analyze black hole solutions in this energy-dependent Gauss-Bonnet gravity's rainbow. We will calculate the modifications to the thermodynamics of black holes in the Gauss-Bonnet's gravity's rainbow. We will demonstrate that even though the thermodynamics of the black holes get modified in the Gauss-Bonnet gravity's rainbow, the first law of thermodynamics still holds for this modified thermodynamics. We will also comment on the thermal stability of the black hole solutions in this theory.
Black hole phase transitions in Horava-Lifshitz gravity
Cao Qiaojun; Chen Yixin; Shao Kainan
2011-03-15
We study black hole phase transitions in (deformed) Horava-Lifshitz (H-L) gravity, including the charged/uncharged topological black holes and KS black hole. Stability analysis and state space geometry are both used. We find interesting phase structures in these black holes, some of the properties are never observed in Einstein gravity. Particularly, the stability properties of black holes in H-L gravity with small radius change dramatically, which can be considered as a leak of information about the small scale behavior of spacetime. A new black hole local phase transition in H-L gravity which cannot be revealed by thermodynamical metrics has been found. There is an infinite discontinuity at the specific heat curve for charged black hole in H-L gravity with hyperbolic event horizon. However, this discontinuity does not have a corresponding curvature singularity of thermodynamical metrics. Our results may provide new insights towards a better understanding of the H-L gravity, as well as black hole thermodynamics.
Black supernovae and black holes in non-local gravity
NASA Astrophysics Data System (ADS)
Bambi, Cosimo; Malafarina, Daniele; Modesto, Leonardo
2016-04-01
In a previous paper, we studied the interior solution of a collapsing body in a non-local theory of gravity super-renormalizable at the quantum level. We found that the classical singularity is replaced by a bounce, after which the body starts expanding. A black hole, strictly speaking, never forms. The gravitational collapse does not create an event horizon but only an apparent one for a finite time. In this paper, we solve the equations of motion assuming that the exterior solution is static. With such an assumption, we are able to reconstruct the solution in the whole spacetime, namely in both the exterior and interior regions. Now the gravitational collapse creates an event horizon in a finite comoving time, but the central singularity is approached in an infinite time. We argue that these black holes should be unstable, providing a link between the scenarios with and without black holes. Indeed, we find a non catastrophic ghost-instability of the metric in the exterior region. Interestingly, under certain conditions, the lifetime of our black holes exactly scales as the Hawking evaporation time.
Black holes and relativitic gravity theories
NASA Technical Reports Server (NTRS)
Fennelly, A. J.; Pavelle, R.
1977-01-01
All presently known relativistic gravitation theories were considered which have a Riemannian background geometry and possess exact static, spherically symmetric solutions which are asymptotically flat. Each theory predicts the existence of trapped surfaces (black holes). For a general static isotropic metric, MACSYMA was used to compute the Newman-Penrose equations, the black hole radius, the impact parameter, and capture radius for photon accretion. These results were then applied to several of the better known gravitation theories.
Thermodynamic instability of black holes of third order Lovelock gravity
Dehghani, M. H.; Pourhasan, R.
2009-03-15
In this paper, we compute the mass and the temperature of the uncharged black holes of third order Lovelock gravity as well as the entropy using the first law of thermodynamics. We perform a stability analysis by studying the curves of the temperature versus the mass parameter, and find that an intermediate thermodynamically unstable phase exists for black holes with a hyperbolic horizon. This unstable phase for the uncharged topological black holes of third order Lovelock gravity does not exist in lower order Lovelock gravity. We also perform a stability analysis for a spherical, seven-dimensional black hole of Lovelock gravity and find that, while these kinds of black holes for small values of Lovelock coefficients have an intermediate unstable phase, they are stable for large values of Lovelock coefficients. We also find that an intermediate unstable phase exists for these black holes in higher dimensions. This analysis shows that the thermodynamic stability of black holes with curved horizons is not a robust feature of all the generalized theories of gravity.
Black holes in an ultraviolet complete quantum gravity
NASA Astrophysics Data System (ADS)
Modesto, Leonardo; Moffat, John W.; Nicolini, Piero
2011-01-01
In this Letter we derive the gravity field equations by varying the action for an ultraviolet complete quantum gravity. Then we consider the case of a static source term and we determine an exact black hole solution. As a result we find a regular spacetime geometry: in place of the conventional curvature singularity extreme energy fluctuations of the gravitational field at small length scales provide an effective cosmological constant in a region locally described in terms of a de Sitter space. We show that the new metric coincides with the noncommutative geometry inspired Schwarzschild black hole. Indeed, we show that the ultraviolet complete quantum gravity, generated by ordinary matter is the dual theory of ordinary Einstein gravity coupled to a noncommutative smeared matter. In other words we obtain further insights about that quantum gravity mechanism which improves Einstein gravity in the vicinity of curvature singularities. This corroborates all the existing literature in the physics and phenomenology of noncommutative black holes.
Probing loop quantum gravity with evaporating black holes.
Barrau, A; Cailleteau, T; Cao, X; Diaz-Polo, J; Grain, J
2011-12-16
This Letter aims at showing that the observation of evaporating black holes should allow the usual Hawking behavior to be distinguished from loop quantum gravity (LQG) expectations. We present a full Monte Carlo simulation of the evaporation in LQG and statistical tests that discriminate between competing models. We conclude that contrarily to what was commonly thought, the discreteness of the area in LQG leads to characteristic features that qualify evaporating black holes as objects that could reveal quantum gravity footprints. PMID:22243065
Astrophysical flows near f (T) gravity black holes
NASA Astrophysics Data System (ADS)
Ahmed, Ayyesha K.; Azreg-Aïnou, Mustapha; Bahamonde, Sebastian; Capozziello, Salvatore; Jamil, Mubasher
2016-05-01
In this paper, we study the accretion process for fluids flowing near a black hole in the context of f( T) teleparallel gravity. Specifically, by performing a dynamical analysis by a Hamiltonian system, we are able to find the sonic points. After that, we consider different isothermal test fluids in order to study the accretion process when they are falling onto the black hole. We find that these flows can be classified according to the equation of state and the black hole features. Results are compared in f( T) and f( R) gravity.
Black hole spectroscopy from loop quantum gravity models
NASA Astrophysics Data System (ADS)
Barrau, Aurelien; Cao, Xiangyu; Noui, Karim; Perez, Alejandro
2015-12-01
Using Monte Carlo simulations, we compute the integrated emission spectra of black holes in the framework of loop quantum gravity (LQG). The black hole emission rates are governed by the entropy whose value, in recent holographic loop quantum gravity models, was shown to agree at leading order with the Bekenstein-Hawking entropy. Quantum corrections depend on the Barbero-Immirzi parameter γ . Starting with black holes of initial horizon area A ˜102 in Planck units, we present the spectra for different values of γ . Each spectrum clearly decomposes into two distinct parts: a continuous background which corresponds to the semiclassical stages of the evaporation and a series of discrete peaks which constitutes a signature of the deep quantum structure of the black hole. We show that γ has an effect on both parts that we analyze in detail. Finally, we estimate the number of black holes and the instrumental resolution required to experimentally distinguish between the considered models.
Quantum gravity effects in black holes at the LHC
NASA Astrophysics Data System (ADS)
Alberghi, G. L.; Casadio, R.; Tronconi, A.
2007-04-01
We study possible back-reaction and quantum gravity effects in the evaporation of black holes which could be produced at the LHC through a modification of the Hawking emission. The corrections are phenomenologically taken into account by employing a modified relation between the black hole mass and temperature. The usual assumption that black holes explode around 1 TeV is also released, and the evaporation process is extended to (possibly much) smaller final masses. We show that these effects could be observable for black holes produced with a relatively large mass and should therefore be taken into account when simulating micro-black hole events for the experiments planned at the LHC.
Linear stability of nonbidiagonal black holes in massive gravity
NASA Astrophysics Data System (ADS)
Babichev, Eugeny; Brito, Richard; Pani, Paolo
2016-02-01
We consider generic linear perturbations of a nonbidiagonal class of static black-hole solutions in massive (bi-)gravity. We show that the quasinormal spectrum of these solutions coincides with that of a Schwarzschild black hole in general relativity, thus proving that these solutions are mode stable. This is in contrast to the case of bidiagonal black-hole solutions which are affected by a radial instability. On the other hand, the full set of perturbation equations is generically richer than that of a Schwarzschild black hole in general relativity, and this affects the linear response of the black hole to external perturbations. Finally, we argue that the generalization of these solutions to the spinning case does not suffer from the superradiant instability, despite the fact that the theory describes a massive graviton.
Phase transitions of black holes in massive gravity
NASA Astrophysics Data System (ADS)
Fernando, Sharmanthie
2016-05-01
In this paper, we have studied thermodynamics of a black hole in massive gravity in the canonical ensemble. The massive gravity theory in consideration here has a massive graviton due to Lorentz symmetry breaking. The black hole studied here has a scalar charge due to the massive graviton and is asymptotically anti-de Sitter (AdS). We have computed various thermodynamical quantities such as temperature, specific heat and free energy. Both the local and global stability of the black hole are studied by observing the behavior of the specific heat and the free energy. We have observed that there is a first-order phase transition between small (SBH) and large black hole (LBH) for a certain range of the scalar charge. This phase transition is similar to the liquid/gas phase transition at constant temperature for a van der Waals fluid. The coexistence curves for the SBH and LBH branches are also discussed in detail.
Notes on black holes and three dimensional gravity
NASA Astrophysics Data System (ADS)
Bañados, Máximo
1999-10-01
In these notes we review some relevant results on 2+1 quantum gravity. These include the Chern-Simons formulation and its affine Kac-Moody symmetry, the asymptotic algebra of Brown and Henneaux, and the statistical mechanics description of 2+1 black holes. A brief introduction to the classical and semiclassical aspects of black holes is also included. The level of the notes is basic assuming only some knowledge on Statistical Mechanics, General Relativity and Yang-Mills theory.
An introduction to spherically symmetric loop quantum gravity black holes
Gambini, Rodolfo; Pullin, Jorge
2015-03-26
We review recent developments in the treatment of spherically symmetric black holes in loop quantum gravity. In particular, we discuss an exact solution to the quantum constraints that represents a black hole and is free of singularities. We show that new observables that are not present in the classical theory arise in the quantum theory. We also discuss Hawking radiation by considering the quantization of a scalar field on the quantum spacetime.
Entropy and temperature of black holes in a gravity's rainbow
Galan, Pablo; Mena Marugan, Guillermo A.
2006-08-15
The linear relation between the entropy and area of a black hole can be derived from the Heisenberg principle, the energy-momentum dispersion relation of special relativity, and general considerations about black holes. There exist results in quantum gravity and related contexts suggesting the modification of the usual dispersion relation and uncertainty principle. One of these contexts is the gravity's rainbow formalism. We analyze the consequences of such a modification for black hole thermodynamics from the perspective of two distinct rainbow realizations built from doubly special relativity. One is the proposal of Magueijo and Smolin and the other is based on a canonical implementation of doubly special relativity put forward recently by the authors. In these scenarios, we obtain modified expressions for the entropy and temperature of black holes. We show that, for a family of doubly special relativity theories satisfying certain properties, the temperature can vanish in the limit of zero black hole mass. For the Magueijo and Smolin proposal, this is only possible for some restricted class of models with bounded energy and unbounded momentum. With the proposal of a canonical implementation, on the other hand, the temperature may vanish for more general theories; in particular, the momentum may also be bounded, with bounded or unbounded energy. This opens new possibilities for the outcome of black hole evaporation in the framework of a gravity's rainbow.
Radiating black hole solutions in Einstein-Gauss-Bonnet gravity
Dominguez, Alfredo E.; Gallo, Emanuel
2006-03-15
In this paper, we find some new exact solutions to the Einstein-Gauss-Bonnet equations. First, we prove a theorem which allows us to find a large family of solutions to the Einstein-Gauss-Bonnet gravity in n-dimensions. This family of solutions represents dynamic black holes and contains, as particular cases, not only the recently found Vaidya-Einstein-Gauss-Bonnet black hole, but also other physical solutions that we think are new, such as the Gauss-Bonnet versions of the Bonnor-Vaidya (de Sitter/anti-de Sitter) solution, a global monopole, and the Husain black holes. We also present a more general version of this theorem in which less restrictive conditions on the energy-momentum tensor are imposed. As an application of this theorem, we present the exact solution describing a black hole radiating a charged null fluid in a Born-Infeld nonlinear electrodynamics.
Greybody factors for a black hole in massive gravity
NASA Astrophysics Data System (ADS)
Dong, Ruifeng; Stojkovic, Dejan
2015-10-01
An exact solution was recently found in the massive gravity theory having the form of Schwarzschild-de Sitter (dS) black holes with some additional background fields. Hawking radiation will occur at the event and cosmological horizons having the blackbody spectrum, which will be modified by the geometry outside the black hole. In this paper, we study the greybody factors of a test scalar, considering its minimal coupling with the background geometry. The case of small black holes with a horizon radius much smaller than the cosmological dS radius is studied numerically. The case of near-extremal black holes with the horizon radius comparable to the cosmological dS radius is studied analytically. In addition, we considered the coupling of the test field with the background Stückelberg fields, which in turn leads to reductions in particle emission and some nontrivial features (resonances) in the greybody factors.
Black hole entropy in canonical quantum gravity and superstring theory
Susskind, L.; Uglum, J. )
1994-08-15
In this paper the entropy of an eternal Schwarzschild black hole is studied in the limit of an infinite black hole mass. The problem is addressed from the point of view of both canonical quantum gravity and superstring theory. The entropy per unit area of a free scalar field propagating in a fixed black hole background is shown to be quadratically divergent near the horizon. It is shown that such quantum corrections to the entropy per unit area are equivalent to the quantum corrections to the gravitational coupling. Unlike field theory, superstring theory provides a set of identifiable configurations which give rise to the classical contribution to the entropy per unit area. These configurations can be understood as open superstrings with both ends attached to the horizon. The entropy per unit area is shown to be finite to all orders in superstring perturbation theory. The importance of these conclusions to the resolution of the problem of black hole information loss is reiterated.
Warped black holes in 3D general massive gravity
NASA Astrophysics Data System (ADS)
Tonni, Erik
2010-08-01
We study regular spacelike warped black holes in the three dimensional general massive gravity model, which contains both the gravitational Chern-Simons term and the linear combination of curvature squared terms characterizing the new massive gravity besides the Einstein-Hilbert term. The parameters of the metric are found by solving a quartic equation, constrained by an inequality that imposes the absence of closed timelike curves. Explicit expressions for the central charges are suggested by exploiting the fact that these black holes are discrete quotients of spacelike warped AdS 3 and a known formula for the entropy. Previous results obtained separately in topological massive gravity and in new massive gravity are recovered as special cases.
Gravitation. [consideration of black holes in gravity theories
NASA Technical Reports Server (NTRS)
Fennelly, A. J.
1978-01-01
Investigations of several problems of gravitation are discussed. The question of the existence of black holes is considered. While black holes like those in Einstein's theory may not exist in other gravity theories, trapped surfaces implying such black holes certainly do. The theories include those of Brans-Dicke, Lightman-Lee, Rosen, and Yang. A similar two-tensor theory of Yilmaz is investigated and found inconsistent and nonviable. The Newman-Penrose formalism for Riemannian geometries is adapted to general gravity theories and used to implement a search for twisting solutions of the gravity theories for empty and nonempty spaces. The method can be used to find the gravitational fields for all viable gravity theories. The rotating solutions are of particular importance for strong field interpretation of the Stanford/Marshall gyroscope experiment. Inhomogeneous cosmologies are examined in Einstein's theory as generalizations of homogeneous ones by raising the dimension of the invariance groups by one more parameter. The nine Bianchi classifications are extended to Rosen's theory of gravity for homogeneous cosmological models.
Thermodynamic instability of nonlinearly charged black holes in gravity's rainbow
NASA Astrophysics Data System (ADS)
Hendi, S. H.; Panahiyan, S.; Panah, B. Eslam; Momennia, M.
2016-03-01
Motivated by the violation of Lorentz invariance in quantum gravity, we study black hole solutions in gravity's rainbow in the context of Einstein gravity coupled with various models of nonlinear electrodynamics. We regard an energy dependent spacetime and obtain the related metric functions and electric fields. We show that there is an essential singularity at the origin which is covered by an event horizon. We also compute the conserved and thermodynamical quantities and examine the validity of the first law of thermodynamics in the presence of rainbow functions. Finally, we investigate the thermal stability conditions for these black hole solutions in the context of canonical ensemble. We show that the thermodynamical structure of the solutions depends on the choices of nonlinearity parameters, charge, and energy functions.
Detecting gravity waves from binary black holes
NASA Technical Reports Server (NTRS)
Wahlquist, Hugo D.
1989-01-01
One of the most attractive possible sources of strong gravitational waves would be a binary system comprising massive black holes (BH). The gravitational radiation from a binary is an elliptically polarized, periodic wave which could be observed continuously - or at intervals whenever a detector was available. This continuity of the signal is certainly appealing compared to waiting for individual pulses from infrequent random events. It also has the advantage over pulses that continued observation can increase the signal-to-noise ratio almost indefinitely. Furthermore, this system is dynamically simple; the theory of the generation of the radiation is unambiguous; all characteristics of the signal can be precisely related to the dynamical parameters of the source. The current situation is that while there is no observational evidence as yet for the existence of massive binary BH, their formation is theoretically plausible, and within certain coupled constraints of mass and location, their existence cannot be observationally excluded. Detecting gravitational waves from these objects might be the first observational proof of their existence.
Black hole hair in generalized scalar-tensor gravity.
Sotiriou, Thomas P; Zhou, Shuang-Yong
2014-06-27
The most general action for a scalar field coupled to gravity that leads to second-order field equations for both the metric and the scalar--Horndeski's theory--is considered, with the extra assumption that the scalar satisfies shift symmetry. We show that in such theories, the scalar field is forced to have a nontrivial configuration in black hole spacetimes, unless one carefully tunes away a linear coupling with the Gauss-Bonnet invariant. Hence, black holes for generic theories in this class will have hair. This contradicts a recent no-hair theorem which seems to have overlooked the presence of this coupling. PMID:25014801
Detailed black hole state counting in loop quantum gravity
Agullo, Ivan; Barbero G, J. Fernando; Borja, Enrique F.; Diaz-Polo, Jacobo; Villasenor, Eduardo J. S.
2010-10-15
We give a complete and detailed description of the computation of black hole entropy in loop quantum gravity by employing the most recently introduced number-theoretic and combinatorial methods. The use of these techniques allows us to perform a detailed analysis of the precise structure of the entropy spectrum for small black holes, showing some relevant features that were not discernible in previous computations. The ability to manipulate and understand the spectrum up to the level of detail that we describe in the paper is a crucial step toward obtaining the behavior of entropy in the asymptotic (large horizon area) regime.
Terminating black holes in asymptotically free quantum gravity
NASA Astrophysics Data System (ADS)
Bambi, Cosimo; Malafarina, Daniele; Modesto, Leonardo
2014-02-01
We study the homogeneous gravitational collapse of a spherical cloud of matter in a super-renormalizable and asymptotically free theory of gravity. We find a picture that differs substantially from the classical scenario. The central singularity appearing in classical general relativity is replaced by a bounce, after which the cloud re-expands indefinitely. We argue that a black hole, strictly speaking, never forms. The collapse only generates a temporary trapped surface, which can be interpreted as a black hole when the observational timescale is much shorter than the one of the collapse. However, it may also be possible that the gravitational collapse produces a black hole and that after the bounce the original cloud of matter evolves into a new universe.
Generating functions for black hole entropy in loop quantum gravity
Barbero G, J. Fernando; Villasenor, Eduardo J. S.
2008-06-15
We introduce, in a systematic way, a set of generating functions that solve all the different combinatorial problems that crop up in the study of black hole entropy in loop quantum gravity. Specifically we give generating functions for the following: the different sources of degeneracy related to the spectrum of the area operator, the solutions to the projection constraint, and the black hole degeneracy spectrum. Our methods are capable of handling the different countings proposed and discussed in the literature. The generating functions presented here provide the appropriate starting point to extend the results already obtained for microscopic black holes to the macroscopic regime - in particular those concerning the area law and the appearance of an effectively equidistant area spectrum.
Quasinormal modes of black holes in Lovelock gravity
NASA Astrophysics Data System (ADS)
Yoshida, Daiske; Soda, Jiro
2016-02-01
We study quasinormal modes of black holes in Lovelock gravity. We formulate the WKB method adapted to Lovelock gravity for the calculation of quasinormal frequencies (QNFs). As a demonstration, we calculate various QNFs of Lovelock black holes in seven and eight dimensions. We find that the QNFs show remarkable features depending on the coefficients of the Lovelock terms, the species of perturbations, and spacetime dimensions. In the case of the scalar field, when we increase the coefficient of the third order Lovelock term, the real part of QNFs increases, but the decay rate becomes small irrespective of the mass of the black hole. For small black holes, the decay rate ceases to depend on the Gauss-Bonnet term. In the case of tensor type perturbations of the metric field, the tendency of the real part of QNFs is opposite to that of the scalar field. The QNFs of vector type perturbations of the metric show no particular behavior. The behavior of QNFs of the scalar type perturbations of the metric field is similar to the vector type. However, available data are rather sparse, which indicates that the WKB method is not applicable to many models for this sector.
Black holes, entropies, and semiclassical spacetime in quantum gravity
NASA Astrophysics Data System (ADS)
Nomura, Yasunori; Weinberg, Sean J.
2014-10-01
We present a coherent picture of the quantum mechanics of black holes. The picture does not require the introduction of any drastically new physical effect beyond what is already known; it arises mostly from synthesizing and (re)interpreting existing results in appropriate manners. We identify the Bekenstein-Hawking entropy as the entropy associated with coarse-graining performed to obtain semiclassical field theory from a fundamental microscopic theory of quantum gravity. This clarifies the issues around the unitary evolution, the existence of the interior spacetime, and the thermodynamic nature in black hole physics — any result in semiclassical field theory is a statement about the maximally mixed ensemble of microscopic quantum states consistent with the specified background, within the precision allowed by quantum mechanics. We present a detailed analysis of information transfer in Hawking emission and black hole mining processes, clarifying what aspects of the underlying dynamics are (not) visible in semiclassical field theory. We also discuss relations between the black hole entropy and the entanglement entropy across the horizon. We then extend our discussions to more general contexts in quantum gravity. The subjects include extensions to de Sitter and Minkowski spaces and implications for complementarity and cosmology, especially the eternally inflating multiverse.
Black hole solutions in 5D Horava-Lifshitz gravity
Koutsoumbas, George; Papantonopoulos, Eletherios; Pasipoularides, Pavlos; Tsoukalas, Minas
2010-06-15
We study the full spectrum of spherically symmetric solutions in the five-dimensional nonprojectable Horava-Lifshitz type gravity theories. For appropriate ranges of the coupling parameters, we have found several classes of solutions which are characterized by an AdS{sub 5}, dS{sub 5}, or flat large distance asymptotic behavior, plus the standard 1/r{sup 2} tail of the usual five-dimensional Schwarzschild black holes. In addition we have found solutions with an unconventional short or large distance behavior, and, for a special range of the coupling parameters, solutions which coincide with black hole solutions of conventional relativistic five-dimensional Gauss-Bonnet gravity.
New 2D dilaton gravity for nonsingular black holes
NASA Astrophysics Data System (ADS)
Kunstatter, Gabor; Maeda, Hideki; Taves, Tim
2016-05-01
We construct a two-dimensional action that is an extension of spherically symmetric Einstein-Lanczos-Lovelock (ELL) gravity. The action contains arbitrary functions of the areal radius and the norm squared of its gradient, but the field equations are second order and obey Birkhoff’s theorem. In complete analogy with spherically symmetric ELL gravity, the field equations admit the generalized Misner-Sharp mass as the first integral that determines the form of the vacuum solution. The arbitrary functions in the action allow for vacuum solutions that describe a larger class of interesting nonsingular black hole spacetimes than previously available.
Minimum length, extra dimensions, modified gravity and black hole remnants
NASA Astrophysics Data System (ADS)
Maziashvili, Michael
2013-03-01
We construct a Hilbert space representation of minimum-length deformed uncertainty relation in presence of extra dimensions. Following this construction, we study corrections to the gravitational potential (back reaction on gravity) with the use of correspondingly modified propagator in presence of two (spatial) extra dimensions. Interestingly enough, for r→0 the gravitational force approaches zero and the horizon for modified Schwarzschild-Tangherlini space-time disappears when the mass approaches quantum-gravity energy scale. This result points out to the existence of zero-temperature black hole remnants in ADD brane-world model.
Topological black holes in Lovelock-Born-Infeld gravity
Dehghani, M. H.; Alinejadi, N.; Hendi, S. H.
2008-05-15
In this paper, we present topological black holes of third order Lovelock gravity in the presence of cosmological constant and nonlinear electromagnetic Born-Infeld field. Depending on the metric parameters, these solutions may be interpreted as black hole solutions with inner and outer event horizons, an extreme black hole or naked singularity. We investigate the thermodynamics of asymptotically flat solutions and show that the thermodynamic and conserved quantities of these black holes satisfy the first law of thermodynamic. We also endow the Ricci flat solutions with a global rotation and calculate the finite action and conserved quantities of these class of solutions by using the counterterm method. We compute the entropy through the use of the Gibbs-Duhem relation and find that the entropy obeys the area law. We obtain a Smarr-type formula for the mass as a function of the entropy, the angular momenta, and the charge, and compute temperature, angular velocities, and electric potential and show that these thermodynamic quantities coincide with their values which are computed through the use of geometry. Finally, we perform a stability analysis for this class of solutions in both the canonical and the grand-canonical ensemble and show that the presence of a nonlinear electromagnetic field and higher curvature terms has no effect on the stability of the black branes, and they are stable in the whole phase space.
NASA Astrophysics Data System (ADS)
Livio, Mario; Koekemoer, Anton M.
2011-02-01
Participants; Preface Mario Livio and Anton Koekemoer; 1. Black holes, entropy, and information G. T. Horowitz; 2. Gravitational waves from black-hole mergers J. G. Baker, W. D. Boggs, J. M. Centrella, B. J. Kelley, S. T. McWilliams and J. R. van Meter; 3. Out-of-this-world physics: black holes at future colliders G. Landsberg; 4. Black holes in globular clusters S. L. W. McMillan; 5. Evolution of massive black holes M. Volonteri; 6. Supermassive black holes in deep multiwavelength surveys C. M. Urry and E. Treister; 7. Black-hole masses from reverberation mapping B. M. Peterson and M. C. Bentz; 8. Black-hole masses from gas dynamics F. D. Macchetto; 9. Evolution of supermassive black holes A. Müller and G. Hasinger; 10. Black-hole masses of distant quasars M. Vestergaard; 11. The accretion history of supermassive black holes K. Brand and the NDWFS Boötes Survey Teams; 12. Strong field gravity and spin of black holes from broad iron lines A. C. Fabian; 13. Birth of massive black-hole binaries M. Colpi, M. Dotti, L. Mayer and S. Kazantzidis; 14. Dynamics around supermassive black holes A. Gualandris and D. Merritt; 15. Black-hole formation and growth: simulations in general relativity S. L. Shapiro; 16. Estimating the spins of stellar-mass black holes J. E. McClintock, R. Narayan and R. Shafee; 17. Stellar relaxation processes near the Galactic massive black hole T. Alexander; 18. Tidal disruptions of stars by supermassive black holes S. Gezari; 19. Where to look for radiatively inefficient accretion flows in low-luminosity AGN M. Chiaberge; 20. Making black holes visible: accretion, radiation, and jets J. H. Krolik.
Exact solutions of three-dimensional black holes: Einstein gravity versus F(R) gravity
NASA Astrophysics Data System (ADS)
Hendi, S. H.; Eslam Panah, B.; Saffari, R.
2014-10-01
In this paper, we consider Einstein gravity in the presence of a class of nonlinear electrodynamics, called power Maxwell invariant (PMI). We take into account (2 + 1)-dimensional spacetime in Einstein-PMI gravity and obtain its black hole solutions. Then, we regard pure F(R) gravity as well as F(R)-conformally invariant Maxwell (CIM) theory to obtain exact solutions of the field equations with black hole interpretation. Finally, we investigate the conserved and thermodynamic quantities and discuss about the first law of thermodynamics for the mentioned gravitational models.
Black Hole Thermodynamic Products in Einstein Gauss Bonnet Gravity
NASA Astrophysics Data System (ADS)
Biswas, Ritabrata
2016-07-01
By now, there are many hints from string theory that collective excitations of solitonic objects can be described by effective low energy theories. The entropy of general rotating black holes in five dimensions may be interpreted as an indication that, it derives from two independent microscopic contributions and each of these may be attributed to a gas of strings. In the present work, we consider a charged black hole in five dimensional Einstein Gauss Bonnet gravity. In spite of presenting the thermodynamic quantities' product as summation/ subtraction of two independent integers, our motive is to check whether the product of the same quantity for event horizon and Cauchy horizon is free of mass, i.e., global, or not. We derive the thermodynamic products of characteristic parameters to mark which are global. We further interpret the stability of the black holes by computing the specific heat for both horizons. Stable and unstable phases of horizons are pointed out. The phase transitions with respect to the charge in nature of specific heat are also observed. All these calculation might be helpful to understand the microscopic nature of such black holes.
Charged black hole solutions in Gauss-Bonnet-massive gravity
NASA Astrophysics Data System (ADS)
Hendi, S. H.; Panahiyan, S.; Panah, B. Eslam
2016-01-01
Motivated by high interest in the close relation between string theory and black hole solutions, in this paper, we take into account the Einstein-Gauss-Bonnet Lagrangian in the context of massive gravity. We examine the possibility of black hole in this regard, and discuss the types of horizons. Next, we calculate conserved and thermodynamic quantities and check the validity of the first law of thermodynamics. In addition, we investigate the stability of these black holes in context of canonical ensemble. We show that number, type and place of phase transition points may be significantly affected by different parameters. Next, by considering cosmological constant as thermodynamical pressure, we will extend phase space and calculate critical values. Then, we construct thermodynamical spacetime by considering mass as thermodynamical potential. We study geometrical thermodynamics of these black holes in context of heat capacity and extended phase space. We show that studying heat capacity, geometrical thermodynamics and critical behavior in extended phase space lead to consistent results. Finally, we will employ a new method for obtaining critical values and show that the results of this method are consistent with those of other methods.
Slowly rotating black holes in alternative theories of gravity
Pani, Paolo; Macedo, Caio F. B.; Crispino, Luis C. B.; Cardoso, Vitor
2011-10-15
We present, in closed analytic form, a general stationary, slowly rotating black hole, which is a solution to a large class of alternative theories of gravity in four dimensions. In these theories, the Einstein-Hilbert action is supplemented by all possible quadratic, algebraic curvature invariants coupled to a scalar field. The solution is found as a deformation of the Schwarzschild metric in general relativity. We explicitly derive the changes to the orbital frequency at the innermost stable circular orbit and at the light ring in closed form. These results could be useful when comparing general relativity against alternative theories by (say) measurements of x-ray emission in accretion disks, or by stellar motion around supermassive black holes. When gravitational-wave astronomy comes into force, strong constraints on the coupling parameters can in principle be made.
Dilaton gravity, charged dust, and (quasi-) black holes
NASA Astrophysics Data System (ADS)
Bronnikov, K. A.; Fabris, J. C.; Silveira, R.; Zaslavskii, O. B.
2014-05-01
We consider Einstein-Maxwell-dilaton gravity with charged dust and interaction of the form P(χ)FμνFμν, where P(χ) is an arbitrary function of the dilaton field χ that can be normal or phantom. For any regular P(χ), static configurations are possible with arbitrary functions g00=exp(2γ(xi)) (i =1, 2, 3) and χ=χ(γ), without any assumption of spatial symmetry. The classical Majumdar-Papapetrou system is restored by putting χ =const. Among possible solutions are black-hole (BH) and quasi-black-hole (QBH) ones. Some general results on BH and QBH properties are deduced and confirmed by examples. It is found, in particular, that asymptotically flat BHs and QBHs can exist with positive energy densities of matter and both scalar and electromagnetic fields.
Statistics, holography, and black hole entropy in loop quantum gravity
NASA Astrophysics Data System (ADS)
Ghosh, Amit; Noui, Karim; Perez, Alejandro
2014-04-01
In loop quantum gravity the quantum states of a black hole horizon consist of pointlike discrete quantum geometry excitations (or punctures) labeled by spin j. The excitations possibly carry other internal degrees of freedom, and the associated quantum states are eigenstates of the area A operator. The appropriately scaled area operator A/(8πℓ) can also be interpreted as the physical Hamiltonian associated with the quasilocal stationary observers located at a small distance ℓ from the horizon. Thus, the local energy is entirely accounted for by the geometric operator A. Assuming that: Close to the horizon the quantum state has a regular energy momentum tensor and hence the local temperature measured by stationary observers is the Unruh temperature. Degeneracy of matter states is exponential with the area exp(λA/ℓp2), which is supported by the well-established results of QFT in curved spacetimes, which do not determine λ but assert an exponential behavior. The geometric excitations of the horizon (punctures) are indistinguishable. And finally that the semiclassical limit the area of the black hole horizon is large in Planck units. It follows that: Up to quantum corrections, matter degrees of freedom saturate the holographic bound, viz., λ must be equal to 1/4. Up to quantum corrections, the statistical black hole entropy coincides with Bekenstein-Hawking entropy S =A/(4ℓp2). The number of horizon punctures goes like N∝√A/ℓp2 ; i.e., the number of punctures N remains large in the semiclassical limit. Fluctuations of the horizon area are small ΔA/A ∝(ℓp2/A)1/4, while fluctuations of the area of an individual puncture are large (large spins dominate). A precise notion of local conformal invariance of the thermal state is recovered in the A→∞ limit where the near horizon geometry becomes Rindler. We also show how the present model (constructed from loop quantum gravity) provides a regularization of (and gives a concrete meaning to) the formal
Thermodynamics of topological black holes in R2 gravity
NASA Astrophysics Data System (ADS)
Cognola, Guido; Rinaldi, Massimiliano; Vanzo, Luciano; Zerbini, Sergio
2015-05-01
We study topological black hole solutions of the simplest quadratic gravity action and we find that two classes are allowed. The first is asymptotically flat and mimics the Reissner-Nordström solution, while the second is asymptotically de Sitter or anti-de Sitter. In both classes, the geometry of the horizon can be spherical, toroidal or hyperbolic. We focus, in particular, on the thermodynamical properties of the asymptotically anti-de Sitter solutions and we compute the entropy and the internal energy with Euclidean methods. We find that the entropy is positive-definite for all horizon geometries and this allows us to formulate a consistent generalized first law of black hole thermodynamics, which keeps in account the presence of two arbitrary parameters in the solution. The two-dimensional thermodynamical state space is fully characterized by the underlying scale invariance of the action and it has the structure of a projective space. We find a kind of duality between black holes and other objects with the same entropy in the state space. We briefly discuss the extension of our results to more general quadratic actions.
Analytic continuation of black hole entropy in Loop Quantum Gravity
NASA Astrophysics Data System (ADS)
Jibril, Ben Achour; Mouchet, Amaury; Noui, Karim
2015-06-01
We define the analytic continuation of the number of black hole microstates in Loop Quantum Gravity to complex values of the Barbero-Immirzi parameter γ. This construction deeply relies on the link between black holes and Chern-Simons theory. Technically, the key point consists in writing the number of microstates as an integral in the complex plane of a holomorphic function, and to make use of complex analysis techniques to perform the analytic continuation. Then, we study the thermodynamical properties of the corresponding system (the black hole is viewed as a gas of indistinguishable punctures) in the framework of the grand canonical ensemble where the energy is defined à la Frodden-Gosh-Perez from the point of view of an observer located close to the horizon. The semi-classical limit occurs at the Unruh temperature T U associated to this local observer. When γ = ± i, the entropy reproduces at the semi-classical limit the area law with quantum corrections. Furthermore, the quantum corrections are logarithmic provided that the chemical potential is fixed to the simple value μ = 2 T U.
Gauge-gravity duality and the black hole interior.
Marolf, Donald; Polchinski, Joseph
2013-10-25
We present a further argument that typical black holes with field theory duals have firewalls at the horizon. This argument makes no reference to entanglement between the black hole and any distant system, and so is not evaded by identifying degrees of freedom inside the black hole with those outside. We also address the Einstein-Rosen=Einstein-Podolsky-Rosen conjecture of Maldacena and Susskind, arguing that the correlations in generic highly entangled states cannot be geometrized as a smooth wormhole. PMID:24206473
Gauge-Gravity Duality and the Black Hole Interior
NASA Astrophysics Data System (ADS)
Marolf, Donald; Polchinski, Joseph
2013-10-01
We present a further argument that typical black holes with field theory duals have firewalls at the horizon. This argument makes no reference to entanglement between the black hole and any distant system, and so is not evaded by identifying degrees of freedom inside the black hole with those outside. We also address the Einstein-Rosen=Einstein-Podolsky-Rosen conjecture of Maldacena and Susskind, arguing that the correlations in generic highly entangled states cannot be geometrized as a smooth wormhole.
Bumpy black holes in alternative theories of gravity
Vigeland, Sarah; Yunes, Nicolas; Stein, Leo C.
2011-05-15
We generalize the bumpy black hole framework to allow for alternative theory deformations. We construct two model-independent parametric deviations from the Kerr metric: one built from a generalization of the quasi-Kerr and bumpy metrics and one built directly from perturbations of the Kerr spacetime in Lewis-Papapetrou form. We find the conditions that these 'bumps' must satisfy for there to exist an approximate second-order Killing tensor so that the perturbed spacetime still possesses three constants of the motion (a deformed energy, angular momentum and Carter constant) and the geodesic equations can be written in first-order form. We map these parametrized metrics to each other via a diffeomorphism and to known analytical black hole solutions in alternative theories of gravity. The parametrized metrics presented here serve as frameworks for the systematic calculation of extreme mass-ratio inspiral waveforms in parametrized non-general relativity theories and the investigation of the accuracy to which space-borne gravitational wave detectors can constrain such deviations.
Dilaton gravity, (quasi-) black holes, and scalar charge
NASA Astrophysics Data System (ADS)
Bronnikov, K. A.; Fabris, J. C.; Silveira, R.; Zaslavskii, O. B.
2014-09-01
We consider static electrically charged dust configurations in the framework of Einstein-Maxwell-dilaton gravity with the interaction term P(\\chi) F_{mn} F^{mn} in the Lagrangian, where P(\\chi) is an arbitrary function of the dilaton field \\chi, and the latter is allowed to be normal or phantom. It is shown that, for any regular P(\\chi), static configurations are possible with arbitrary functions g_{00} = e^{2\\gamma(x^i)} (i=1,2,3) and \\chi = \\chi(\\gamma), without any assumption of spatial symmetry. The corresponding matter, electric charge and scalar charge densities are found from the field equations. Meanwhile, configurations with nontrivial \\chi(x^i) generically require a nonzero scalar charge density distribution. The classical Majumdar-Papapetrou (MP) system is obtained as a special case where \\chi = const; there is its scalar analogue in the case F_{mn} = 0, but only with a phantom \\chi field. Among possible solutions are black-hole (BH) and quasi-black-hole (QBH) ones. Some general results on QBH properties obtained previously for the MP system are here extended to systems with the dilaton. Particular examples of asymptotically flat spherically symmetric BH and QBH solutions are found, some of them being phantom-free, that is, exist with positive energy densities of matter and both scalar and electromagnetic fields.
Black hole initial data in Gauss-Bonnet gravity: Momentarily static case
Yoshino, Hirotaka
2011-05-15
We study the method for generating the initial data of black hole systems in Gauss-Bonnet gravity. The initial data are assumed to be momentarily static and conformally flat. Although the equation for the conformal factor is highly nonlinear, it is successfully solved by numerical relaxation for one-black-hole and two-black-hole systems. The common apparent horizon is studied in the two-black-hole initial data, and the result suggests that the Penrose inequalities are satisfied in this system. This is the first step for simulating black hole collisions in higher-curvature theories.
Another approach to test gravity around a black hole
NASA Astrophysics Data System (ADS)
Iwata, Kengo; Yoo, Chul-Moon
2016-08-01
Pulsars orbiting around the black hole (BH) at our galactic center provide us with a unique testing site for gravity. In this work, we propose an approach to probe the gravity around the BH introducing two phenomenological parameters which characterize deviation from the vacuum Einstein theory. The two phenomenological parameters are associated with the energy–momentum tensor in the framework of the Einstein theory. Therefore, our approach can be regarded as the complement to the parametrized post-Newtonian framework in which phenomenological parameters are introduced for deviation of gravitational theories from general relativity. In our formulation, we take into account the possibility of existence of a relativistic and exotic matter component. Since the pulsars can be regarded as test particles, as the first step, we consider geodesic motion in the system composed of a central BH and a perfect fluid whose distribution is static and spherically symmetric. It is found that the mass density of the fluid and a parameter of the equation of state can be determined with precision with 0.1 % if the density on the pulsar orbit is larger than {10}-9 {{g}} {{cm}}-3.
Charged rotating Kaluza-Klein black holes in dilaton gravity
Allahverdizadeh, Masoud; Matsuno, Ken; Sheykhi, Ahmad
2010-02-15
We obtain a class of slowly rotating charged Kaluza-Klein black hole solutions of the five-dimensional Einstein-Maxwell-dilaton theory with arbitrary dilaton coupling constant. At infinity, the spacetime is effectively four dimensional. In the absence of the squashing function, our solution reduces to the five-dimensional asymptotically flat slowly rotating charged dilaton black hole solution with two equal angular momenta. We calculate the mass, the angular momentum, and the gyromagnetic ratio of these rotating Kaluza-Klein dilaton black holes. It is shown that the dilaton field and the nontrivial asymptotic structure of the solutions modify the gyromagnetic ratio of the black holes. We also find that the gyromagnetic ratio crucially depends on the dilaton coupling constant, {alpha}, and decreases with increasing {alpha} for any size of the compact extra dimension.
Horizons of radiating black holes in Einstein-Gauss-Bonnet gravity
Ghosh, S. G.; Deshkar, D. W.
2008-02-15
A Vaidya-based model of a radiating black hole is studied in a 5-dimensional Einstein gravity with Gauss-Bonnet contribution of quadratic curvature terms. The structure and locations of the apparent and event horizons of the radiating black hole are determined.
Phenomenology of bouncing black holes in quantum gravity: a closer look
NASA Astrophysics Data System (ADS)
Barrau, Aurélien; Bolliet, Boris; Vidotto, Francesca; Weimer, Celine
2016-02-01
It was recently shown that black holes could be bouncing stars as a consequence of quantum gravity. We investigate the astrophysical signals implied by this hypothesis, focusing on primordial black holes. We consider different possible bounce times and study the integrated diffuse emission.
Extremal Black Holes in Dynamical Chern-Simons Gravity
NASA Astrophysics Data System (ADS)
Stein, Leo; McNees, Robert; Yunes, Nicolas
2016-03-01
Analytic solutions are rare and precious in general relativity, even more so in theories beyond GR. From them we can calculate observational signals of beyond-GR physics, but also learn about the analytic structure of theories, which can't be done with numerics. Despite over a decade of searching, nobody has yet succeeded in finding an analytic form for a generically rotating black hole in dynamical Chern-Simons gravity (dCS), the simplest beyond-GR theory which includes a parity-odd interaction. In this talk we present progress towards a full solution by considering the extremal limit. We treat dCS in the decoupling limit, taking corrections as small perturbations away from GR. We perturb about extremal Kerr, and develop mathematical insight into the techniques needed to construct solutions for general spin. We find closed-form analytic expressions for the scalar field and a formal solution for the trace of the metric deformation, both in Legendre series. The first three (four) modes of the series of the scalar (metric trace) suffice to ensure a fidelity of over 99% relative to numerical solutions. The monopole of the metric trace contains a logarithmic divergence at the extremal Kerr horizon, which is likely hidden behind the perturbed dCS horizon.
Stars and (furry) black holes in Lorentz breaking massive gravity
Comelli, D.; Nesti, F.; Pilo, L.
2011-04-15
We study the exact spherically symmetric solutions in a class of Lorentz-breaking massive gravity theories, using the effective-theory approach where the graviton mass is generated by the interaction with a suitable set of Stueckelberg fields. We find explicitly the exact black-hole solutions which generalizes the familiar Schwarzschild one, which shows a nonanalytic hair in the form of a powerlike term r{sup {gamma}}. For realistic self-gravitating bodies, we find interesting features, linked to the effective violation of the Gauss law: (i) the total gravitational mass appearing in the standard 1/r term gets a multiplicative renormalization proportional to the area of the body itself; (ii) the magnitude of the powerlike hairy correction is also linked to size of the body. The novel features can be ascribed to the presence of the Goldstones fluid turned on by matter inside the body; its equation of state approaching that of dark energy near the center. The Goldstones fluid also changes the matter equilibrium pressure, leading to an upper limit for the graviton mass, m < or approx. 10{sup -28/29} eV, derived from the largest stable gravitational bound states in the Universe.
Scalar and spinor QNMs of a black hole with a global monopole in f ( R) gravity
NASA Astrophysics Data System (ADS)
Graça, J. P. Morais; Vieira, H. S.; Bezerra, V. B.
2016-04-01
The quasinormal modes for scalar and spinor fields in the background spacetime corresponding to a black hole with a global monopole in f( R) gravity are calculated using the WKB approximation. In the obtained results we emphasize the role played by the parameter ψ 0, associated with the f ( R) gravity. We discuss the appropriate limit ψ 0 → 0, in which case the results concerning to the Schwarzschild black hole are obtained, as it should be expected.
Charged Fermions Tunnel from the Kerr-Newman Black Hole Influenced by Quantum Gravity Effects
NASA Astrophysics Data System (ADS)
Ren, Ruyi; Chen, Deyou; Pu, Jin
2016-03-01
Taking into account quantum gravity effects, we investigate the tunnelling radiation of charged fermions in the Kerr-Newman black hole. The result shows that the corrected Hawking temperature is determined not only by the parameters of the black hole, but also by the energy, angular momentum and mass of the emitted fermion. Meanwhile, an interesting found is that the temperature is affected by the angle 𝜃. The quantum gravity correction slows down the evaporation.
Generalized uncertainty principle in f(R) gravity for a charged black hole
Said, Jackson Levi; Adami, Kristian Zarb
2011-02-15
Using f(R) gravity in the Palatini formularism, the metric for a charged spherically symmetric black hole is derived, taking the Ricci scalar curvature to be constant. The generalized uncertainty principle is then used to calculate the temperature of the resulting black hole; through this the entropy is found correcting the Bekenstein-Hawking entropy in this case. Using the entropy the tunneling probability and heat capacity are calculated up to the order of the Planck length, which produces an extra factor that becomes important as black holes become small, such as in the case of mini-black holes.
A note on Schwarzschild-de Sitter black holes in mimetic F(R) gravity
NASA Astrophysics Data System (ADS)
Oikonomou, V. K.
2016-05-01
In this paper, we investigate the conditions under which a Schwarzschild-de Sitter black hole spacetime is a solution of the mimetic F(R) gravity with Lagrange multiplier and potential. As we demonstrate, the resulting mimetic F(R) gravity is a slight modification of the ordinary F(R) gravity case, however the resulting perturbation equations are not in all cases identical to the ordinary F(R) gravity case. In the latter case, the perturbation equations are identical to the ones corresponding to the Reissner-Nordström anti-de Sitter black hole.
Warped AdS3 black holes in higher derivative gravity theories
NASA Astrophysics Data System (ADS)
Detournay, Stéphane; Douxchamps, Laure-Anne; Ng, Gim Seng; Zwikel, Céline
2016-06-01
We consider warped AdS3 black holes in generic higher derivatives gravity theories in 2+1 dimensions. The asymptotic symmetry group of the phase space containing these black holes is the semi-direct product of a centrally extended Virasoro algebra and an affine u(1) Kac-Moody algebra. Previous works have shown that in some specific theories, the entropy of these black holes agrees with a Cardy-like entropy formula derived for warped conformal field theories. In this paper, we show that this entropy matching continues to hold for the most general higher derivative theories of gravity. We also discuss the existence of phase transitions.
The fate of Schwarzschild-de Sitter black holes in f(R) gravity
NASA Astrophysics Data System (ADS)
Addazi, Andrea; Capozziello, Salvatore
2016-03-01
The semiclassical effects of anti-evaporating black holes can be discussed in the framework of f(R) gravity. In particular, the Bousso-Hawking-Nojiri-Odinstov anti-evaporation instability of degenerate Schwarzschild-de Sitter black holes (the so-called Nariai spacetime) leads to a dynamical increasing of black hole horizon in f(R) gravity. This phenomenon causes the following transition: emitting marginally trapped surfaces (TS) become space-like surfaces before the effective Bekenstein-Hawking emission time. As a consequence, Bousso-Hawking thermal radiation cannot be emitted in an anti-evaporating Nariai black hole. Possible implications in cosmology and black hole physics are also discussed.
Anomalies and Hawking fluxes from the black holes of topologically massive gravity
NASA Astrophysics Data System (ADS)
Porfyriadis, Achilleas P.
2009-05-01
The anomaly cancelation method proposed by Wilczek et al. is applied to the black holes of topologically massive gravity (TMG) and topologically massive gravito-electrodynamics (TMGE). Thus the Hawking temperature and fluxes of the ACL and ACGL black holes are found. The Hawking temperatures obtained agree with the surface gravity formula. Both black holes are rotating and this gives rise to appropriate terms in the effective U (1) gauge field of the reduced (1 + 1)-dimensional theory. It is found that the terms in this U (1) gauge field correspond exactly to the correct angular velocities on the horizon of both black holes as well as the correct electrostatic potential of the ACGL black hole. So the results for the Hawking fluxes derived here from the anomaly cancelation method, are in complete agreement with the ones obtained from integrating the Planck distribution.
Spectroscopy of a charged black hole in gravity's rainbow via an action invariance
NASA Astrophysics Data System (ADS)
Liu, Chengzhou; Liu, Haiwen
2015-06-01
The spectroscopy of a modified Reissner-Nordstrom black hole in gravity's rainbow was investigated. By utilizing an action invariance of the black hole and with the help of Bohr-Sommerfield quantization rule, the entropy and area spectrum for the quantum corrected charged black hole were calculated. The equally spaced entropy spectrum being consistent to the original Bekenstein's spectrum was derived. However, due to the spacetime quantum effect of the gravity's rainbow, the obtained area spectra was not equally spaced and the area spacing depend on the horizon area. And that, the quantum corrections of the area spectrum and the black hole entropy to the original Bekenstein's results were discussed. Besides, it was found that, the entropy and area spectrum of the modified charged black hole were independent of the energy of the test particle, although the modified spacetime itself has the energy dependence.
Topological black holes in pure Gauss-Bonnet gravity and phase transitions
NASA Astrophysics Data System (ADS)
Aránguiz, Ligeia; Kuang, Xiao-Mei; Miskovic, Olivera
2016-03-01
We study charged, static, topological black holes in pure Gauss-Bonnet gravity in asymptotically AdS space. As in general relativity, the theory possesses a unique nondegenerate AdS vacuum. It also admits charged black hole solutions which asymptotically behave as the Reissner-Nordström AdS black hole. We discuss black hole thermodynamics of these black holes. Then we study phase transitions in a dual quantum field theory in four dimensions, with the Stückelberg scalar field as an order parameter. We find in the probe limit that the black hole can develop hair below some critical temperature, which suggests a phase transition. Depending on the scalar coupling constants, the phase transition can be first or second order. Analysis of the free energy reveals that, comparing the two solutions, the hairy state is energetically favorable, thus a phase transition will occur in a dual field theory.
Nature of Microscopic Black Holes and Gravity in Theories with Particle Species
NASA Astrophysics Data System (ADS)
Dvali, Gia
Relying solely on unitarity and the consistency with large-distance black hole physics, we derive model-independent properties of the microscopic black holes and of short-distance gravity in theories with N particle species. In this class of theories black holes can be as light as MPlanck /√ N and be produced in particle collisions above this energy. We show, that the micro black holes must come in the same variety as the species do, although their label is not associated with any conserved charge measurable at large distances. In contrast with big Schwarzschildian ones, the evaporation of the smallest black holes is maximally undemocratic and is biased in favor of particular species. With an increasing mass the democracy characteristic to the usual macro black holes is gradually regained. The lowest possible mass above which black holes become Einsteinian is √ N MPlanck . This fact uncovers the new fundamental scale (below the quantum gravity scale) above which gravity changes classically, and the properties of black holes and gravity are such as if some extra dimensions open up, although no such input exists in the theory. Our observations indicate that geometry of space may be an emergent concept following from large number of species and the consistency with macro black hole physics. We apply our findings to the phenomenological properties of the micro black holes that can be observed at LHC for large N. Extrapolating our findings to small N, one may ask whether the existence of quark and lepton flavors is already an evidence for emergent extra dimensions at short distances.
Nature of Microscopic Black Holes and Gravity in Theories with Particle Species
NASA Astrophysics Data System (ADS)
Dvali, Gia
2010-01-01
Relying solely on unitarity and the consistency with large-distance black hole physics, we derive model-independent properties of the microscopic black holes and of short-distance gravity in theories with N particle species. In this class of theories black holes can be as light as MPlanck /√ N and be produced in particle collisions above this energy. We show, that the micro black holes must come in the same variety as the species do, although their label is not associated with any conserved charge measurable at large distances. In contrast with big Schwarzschildian ones, the evaporation of the smallest black holes is maximally undemocratic and is biased in favor of particular species. With an increasing mass the democracy characteristic to the usual macro black holes is gradually regained. The lowest possible mass above which black holes become Einsteinian is √ N MPlanck . This fact uncovers the new fundamental scale (below the quantum gravity scale) above which gravity changes classically, and the properties of black holes and gravity are such as if some extra dimensions open up, although no such input exists in the theory. Our observations indicate that geometry of space may be an emergent concept following from large number of species and the consistency with macro black hole physics. We apply our findings to the phenomenological properties of the micro black holes that can be observed at LHC for large N. Extrapolating our findings to small N, one may ask whether the existence of quark and lepton flavors is already an evidence for emergent extra dimensions at short distances.
Gravity-dominated unequal-mass black hole collisions
NASA Astrophysics Data System (ADS)
Sperhake, Ulrich; Berti, Emanuele; Cardoso, Vitor; Pretorius, Frans
2016-02-01
We continue our series of studies of high-energy collisions of black holes investigating unequal-mass, boosted head-on collisions in four dimensions. We show that the fraction of the center-of-mass energy radiated as gravitational waves becomes independent of mass ratio and approximately equal to 13% at large energies. We support this conclusion with calculations using black hole perturbation theory and Smarr's zero-frequency limit approximation. These results lend strong support to the conjecture that the detailed structure of the colliding objects is irrelevant at high energies.
Thermodynamics of asymptotically flat charged black holes in third order Lovelock gravity
Dehghani, M.H.; Shamirzaie, M.
2005-12-15
We present a new class of asymptotically flat charge static solutions in third order Lovelock gravity. These solutions present black hole solutions with two inner and outer event horizons, extreme black holes, or naked singularities provided the parameters of the solutions are chosen suitable. We find that the uncharged asymptotically flat solutions can present black holes with two inner and outer horizons. This kind of solution does not exist in Einstein or Gauss-Bonnet gravity, and it is a special effect in third order Lovelock gravity. We compute temperature, entropy, charge, electric potential, and mass of the black hole solutions, and find that these quantities satisfy the first law of thermodynamics. We also perform a stability analysis by computing the determinant of the Hessian matrix of the mass with respect to its thermodynamic variables in both the canonical and the grand-canonical ensembles, and show that there exists only an intermediate stable phase.
Quantum Gravity Effects on the Tunneling Radiation of the Einstein-Maxwell-Dilaton-Axion Black Hole
NASA Astrophysics Data System (ADS)
Cheng, Tianhu; Ren, Ruyi; Chen, Deyou; Liu, Zixiang; Li, Guopin
2016-07-01
Taking into account effects of quantum gravity, we investigate the evaporation of an Einstein-Maxwell-Dilaton-Axion black hole. The corrected Hawking temperature is gotten respectively by the scalar particle's and the fermion's tunneling across the horizon. This temperature is lower than the original one derived by Hawking, which means quantum gravity effects slow down the rise of the temperature.
Violation of the first law of black hole thermodynamics in f(T) gravity
Miao, Rong-Xin; Li, Miao; Miao, Yan-Gang E-mail: mli@itp.ac.cn
2011-11-01
We prove that, in general, the first law of black hole thermodynamics, δQ = TδS, is violated in f(T) gravity. As a result, it is possible that there exists entropy production, which implies that the black hole thermodynamics can be in non-equilibrium even in the static spacetime. This feature is very different from that of f(R) or that of other higher derivative gravity theories. We find that the violation of first law results from the lack of local Lorentz invariance in f(T) gravity. By investigating two examples, we note that f''(0) should be negative in order to avoid the naked singularities and superluminal motion of light. When f''(T) is small, the entropy of black holes in f(T) gravity is approximatively equal to f'(T)/4 A.
Quasinormal modes for single horizon black holes in generic 2D dilaton gravity
NASA Astrophysics Data System (ADS)
Kettner, Joanne; Kunstatter, Gabor; Medved, A. J. M.
2004-12-01
There has been some recent speculation that a connection may exist between the quasinormal-mode spectra of highly damped black holes and the fundamental theory of quantum gravity. This notion follows from a conjecture by Hod that the real part of the highly damped mode frequencies can be used to calibrate the semi-classical level spacing in the black-hole quantum area spectrum. However, even if the level spacing can be fixed in this manner, it still remains unclear whether this implies a physically significant 'duality' or merely a numerical coincidence. This tapestry of ideas serves as the motivation for the current paper. We utilize the 'monodromy approach' to calculate the quasinormal-mode spectra for a generic class of black holes in two-dimensional dilatonic gravity. Our results agree with the prior literature whenever a direct comparison is possible and provide the analysis of a much more diverse class of black-hole models than previously considered.
Rotating black holes in a draining bathtub: Superradiant scattering of gravity waves
NASA Astrophysics Data System (ADS)
Richartz, Maurício; Prain, Angus; Liberati, Stefano; Weinfurtner, Silke
2015-06-01
In a draining rotating fluid flow background, surface perturbations behave as a scalar field on a rotating effective black hole spacetime. We propose a new model for the background flow which takes into account the varying depth of the water. Numerical integration of the associated Klein-Gordon equation using accessible experimental parameters shows that gravity waves in an appropriate frequency range are amplified through the mechanism of superradiance. Our numerical results suggest that the observation of this phenomenon in a common fluid mechanical system is within experimental reach. Unlike the case of wave scattering around Kerr black holes, which depends only on one dimensionless background parameter (the ratio a /M between the specific angular momentum and the mass of the black hole), our system depends on two dimensionless background parameters, namely the normalized angular velocity and surface gravity at the effective black hole horizon.
Influence of self-gravity on the runaway instability of black-hole-torus systems.
Montero, Pedro J; Font, José A; Shibata, Masaru
2010-05-14
Results from the first fully general relativistic numerical simulations in axisymmetry of a system formed by a black hole surrounded by a self-gravitating torus in equilibrium are presented, aiming to assess the influence of the torus self-gravity on the onset of the runaway instability. We consider several models with varying torus-to-black-hole mass ratio and angular momentum distribution orbiting in equilibrium around a nonrotating black hole. The tori are perturbed to induce the mass transfer towards the black hole. Our numerical simulations show that all models exhibit a persistent phase of axisymmetric oscillations around their equilibria for several dynamical time scales without the appearance of the runaway instability, indicating that the self-gravity of the torus does not play a critical role favoring the onset of the instability, at least during the first few dynamical time scales. PMID:20866955
Thermodynamical first laws of black holes in quadratically-extended gravities
NASA Astrophysics Data System (ADS)
Fan, Zhong-Ying; Lü, H.
2015-03-01
Einstein gravities in general dimensions coupled to a cosmological constant and extended with quadratic curvature invariants admit a variety of black holes that may asymptote to Minkowski, anti-de Sitter or Lifshitz spacetimes. We adopt the Wald formalism to derive an explicit formula for calculating the thermodynamical first law for the static black holes with spherical, toric, or hyperbolic isometries in these theories. This allows us to derive or rederive the first laws for a wide range of black holes in the literature. Furthermore, we construct many new exact solutions and obtain their first laws.
Static black holes of metric-affine gravity in the presence of matter
NASA Astrophysics Data System (ADS)
Ayón-Beato, Eloy; García, Alberto; Macías, Alfredo; Quevedo, Hernando
2001-07-01
We investigate spherically symmetric and static gravitational fields representing black hole configurations in the framework of metric-affine gauge theories of gravity (MAG) in the presence of different matter fields. It is shown that in the triplet ansatz sector of MAG, black hole configurations in the presence of non-Abelian matter fields allow the existence of black hole hair. We analyze several cases of matter fields characterized by the presence of hair and for all of them we show the validity of the no short hair conjecture.
- criticality of AdS black hole in the Einstein-Maxwell-power-Yang-Mills gravity
NASA Astrophysics Data System (ADS)
Zhang, Ming; Yang, Zhan-Ying; Zou, De-Cheng; Xu, Wei; Yue, Rui-Hong
2015-02-01
We study the - critical behaivor of N-dimensional AdS black holes in Einstein-Maxwell-power-Yang-Mills gravity. Our results show the existence of the Van der Waals like small-large black hole phase transitions when taking some special values of charges of the Maxwell and Yang-Mills fields. Further to calculate the critical exponents of the black holes at the critical point, we find that they are the same as those in the Van der Waals liquid-gas system.
NASA Astrophysics Data System (ADS)
Husain, Viqar
2012-03-01
researchers in other areas who wish to learn about the canonical approach to gravity. However, given the brief chapter on quantization, the book would go well with a review paper, or parts of the other three quantum gravity books cited above. References [1] Kiefer C 2006 Quantum Gravity 2nd ed. (Oxford University Press) [2] Rovelli C 2007 Quantum Gravity (Cambridge University Press) [3] Thiemann T 2008 Modern Canonical Quantum Gravity (Cambridge University Press) [4] Posson E 2004 A Relativist's Toolkit: The Mathematics of Black-Hole Mechanics (Cambridge University Press) [5] Ryan M P and Shepley L C 1975 Homogeneous Relativistic Cosmology (Princeton University Press)
Hawking, fiducial, and free-fall temperature of black hole on gravity's rainbow
NASA Astrophysics Data System (ADS)
Gim, Yongwan; Kim, Wontae
2016-03-01
On gravity's rainbow, the energy of test particles deforms the geometry of a black hole in such a way that the corresponding Hawking temperature is expected to be modified. It means that the fiducial and free-fall temperatures on the black hole background should also be modified according to deformation of the geometry. In this work, the probing energy of test particles is assumed as the average energy of the Hawking particle in order to study the particle back reaction of the geometry by using the advantage of gravity's rainbow. We shall obtain the modified fiducial and free-fall temperatures, respectively. The behaviors of these two temperatures on the horizon tell us that black hole complementarity is still well defined on gravity's rainbow.
Brügmann, B.; Ghez, A. M.; Greiner, J.
2001-01-01
Recent progress in black hole research is illustrated by three examples. We discuss the observational challenges that were met to show that a supermassive black hole exists at the center of our galaxy. Stellar-size black holes have been studied in x-ray binaries and microquasars. Finally, numerical simulations have become possible for the merger of black hole binaries. PMID:11553801
Tunnelling of relativistic particles from new type black hole in new massive gravity
NASA Astrophysics Data System (ADS)
Gecim, Ganim; Sucu, Yusuf
2013-02-01
In the framework of the three dimensional New Massive Gravity theory introduced by Bergshoeff, Hohm and Townsend, we analyze the behavior of relativistic spin-1/2 and spin-0 particles in the New-type Black Hole backgroud, solution of the New Massive Gravity.We solve Dirac equation for spin-1/2 and Klein-Gordon equation for spin-0. Using Hamilton-Jacobi method, we discuss tunnelling probability and Hawking temperature of the spin-1/2 and spin-0 particles for the black hole. We observe that the tunnelling probability and Hawking temperature are same for the spin-1/2 and spin-0.
Membrane paradigm of black holes in Chern-Simons modified gravity
NASA Astrophysics Data System (ADS)
Zhao, Tian-Yi; Wang, Towe
2016-06-01
The membrane paradigm of black hole is studied in the Chern-Simons modified gravity. Derived with the action principle a la Parikh-Wilczek, the stress tensor of membrane manifests a rich structure arising from the Chern-Simons term. The membrane stress tensor, if related to the bulk stress tensor in a special form, obeys the low-dimensional fluid continuity equation and the Navier-Stokes equation. This paradigm is applied to spherically symmetric static geometries, and in particular, the Schwarzschild black hole, which is a solution of a large class of dynamical Chern-Simons gravity.
Fermions Tunnelling from Black String and Kerr AdS Black Hole with Consideration of Quantum Gravity
NASA Astrophysics Data System (ADS)
Li, Zhong-hua; Zhang, Li-mei
2016-01-01
In this paper, using the Hamilton-Jacobi Ansatz, we discuss the tunnelling of fermions when effects of quantum gravity are taken into account. We investigate two cases, black string and Kerr AdS black hole. For black string, the uncharged and un-rotating case, we find that the correction of Hawking temperature is only affected by the mass of emitted fermions and the quantum gravitational corrections slow down the increases of the temperature, which naturally leads to remnants left in the evaporation. For another case, the Kerr AdS black hole, we find that the quantum gravitational corrections are not only determined by the mass of the emitted fermions but also affected by the rotating properties of the AdS black hole. So with consideration of the quantum gravity corrections, an offset around the standard temperature always exists.
Topological black holes for Einstein-Gauss-Bonnet gravity with a nonminimal scalar field
NASA Astrophysics Data System (ADS)
Gaete, Moisés Bravo; Hassaïne, Mokhtar
2013-11-01
We consider the Einstein-Gauss-Bonnet gravity with a negative cosmological constant together with a source given by a scalar field nonminimally coupled in arbitrary dimension D. For a certain election of the cosmological and Gauss-Bonnet coupling constants, we derive two classes of AdS black hole solutions whose horizon is planar. The first family of black holes obtained for a particular value of the nonminimal coupling parameter only depends on a constant M, and the scalar field vanishes as M=0. The second class of solutions corresponds to a two-parametric (with constants M and A) black hole stealth configuration, which is a nontrivial scalar field with a black hole metric such that both sides (gravity and matter parts) of the Einstein equations vanish. In this case, in the vanishing M, the solution reduces to a stealth scalar field on the pure AdS metric. We note that the existence of these two classes of solutions is indicative of the particular choice of the coupling constants, and they cannot be promoted to spherical or hyperboloid black hole solutions in a standard fashion. In the last part, we add to the original action some exact (D-1) forms coupled to the scalar field. The direct benefit of introducing such extra fields is to obtain black hole solutions with a planar horizon for an arbitrary value of the nonminimal coupling parameter.
Anisotropic scale invariant spacetimes and black holes in Zwei-Dreibein Gravity
NASA Astrophysics Data System (ADS)
Goya, A. F.
2014-09-01
We show that Zwei-Dreibein Gravity (ZDG), a bigravity theory recently proposed by Bergshoeff, de Haan, Hohm, Merbis, and Townsend in ref. [1], admits exact solutions with anisotropic scale invariance. These type of geometries are the three-dimensional analogues of the spacetimes which were proposed as gravity duals for condensed matter systems. In particular, we find Schrödinger invariant spaces as well as Lifshitz spaces with arbitrary dynamical exponent z. We also find black holes that are asymptotically Lifshitz with z = 3, showing that these (non-constant curvature) solutions of New Massive Gravity (NMG) are persistent after the introduction of the infinite tower of higher-curvature terms of ZDG, provided a renormalization of the parameters. Black holes in asymptotically warped Anti-de Sitter spaces are also found. Interestingly, in almost all the geometries studied in this work, the metric associated with the second dreibein turns out to be equivalent, up to a constant global factor, to the first one. This phenomenon has been previously observed in other bigravity theories in asymptotically flat and asymptotically Anti-de Sitter backgrounds. However, for the particular case of the z = 3 Lifshitz black hole, here we found that the second metric corresponds to a different black hole that coincides with the former only in the asymptotic region. In fact, we find a new family of z = 3 black holes that corresponds to a one-parameter deformation of the NMG solution.
Brown-York quasilocal energy in Lanczos-Lovelock gravity and black hole horizons
NASA Astrophysics Data System (ADS)
Chakraborty, Sumanta; Dadhich, Naresh
2015-12-01
A standard candidate for quasilocal energy in general relativity is the Brown-York energy, which is essentially a two dimensional surface integral of the extrinsic curvature on the two-boundary of a spacelike hypersurface referenced to flat spacetime. Several years back one of us had conjectured that the black hole horizon is defined by equipartition of gravitational and non-gravitational energy. By employing the above definition of quasilocal Brown-York energy, we have verified the equipartition conjecture for static charged and charged axi-symmetric black holes in general relativity. We have further generalized the Brown-York formalism to all orders in Lanczos-Lovelock theories of gravity and have verified the conjecture for pure Lovelock charged black hole in all even d = 2 m + 2 dimensions, where m is the degree of Lovelock action. It turns out that the equipartition conjecture works only for pure Lovelock, and not for Einstein-Lovelock black holes.
Thermodynamics of black holes in (n+1)-dimensional Einstein-Born-Infeld-dilaton gravity
Sheykhi, A.; Riazi, N.
2007-01-15
We construct a new class of (n+1)-dimensional (n{>=}3) black hole solutions in Einstein-Born-Infeld-dilaton gravity with Liouville-type potential for the dilaton field and investigate their properties. These solutions are neither asymptotically flat nor (anti)-de Sitter. We find that these solutions can represent black holes, with inner and outer event horizons, an extreme black hole, or a naked singularity provided the parameters of the solutions are chosen suitably. We compute the thermodynamic quantities of the black hole solutions and find that these quantities satisfy the first law of thermodynamics. We also perform a stability analysis and investigate the effect of dilaton on the stability of the solutions.
Quantum-gravity effects outside the horizon spark black to white hole tunneling
NASA Astrophysics Data System (ADS)
Haggard, Hal M.; Rovelli, Carlo
2015-11-01
We show that there is a classical metric satisfying the Einstein equations outside a finite spacetime region where matter collapses into a black hole and then emerges from a white hole. We compute this metric explicitly. We show how quantum theory determines the (long) time for the process to happen. A black hole can thus quantum tunnel into a white hole. For this to happen, quantum gravity should affect the metric also in a small region outside the horizon; we show that, contrary to what is commonly assumed, this is not forbidden by causality or by the semiclassical approximation, because quantum effects can pile up over a long time. This scenario alters radically the discussion on the black hole information puzzle.
Gauge/ gravity correspondence, bulk locality and quantum black holes
NASA Astrophysics Data System (ADS)
Sarkar, Debajyoti
The aim of this dissertation is threefold. We begin by the study of two parallel ideal cosmic strings in the presence of non-minimal scalar fields and spin- 1 gauge fields. We show that the contributions of the non-minimal term on the interaction energy between the strings are similar to that of the gauge field for a particular value of non-minimal coupling parameter. In this context we clarify some of the issues that arise when comparing the renormalization of black hole entropy and entanglement entropy using the replica trick. In the second part of the dissertation we study the process of bound state formation in clusters of Dp- brane collision and Dp shell/ Membrane collapse processes. We consider two mechanisms for bound state formation. The first, operative at weak coupling in the worldvolume gauge theory, is creation of W-bosons. The second, operative at strong coupling, corresponds to formation of a black hole in the dual supergravity. These two processes agree qualitatively at intermediate coupling, in accord with the correspondence principle of Horowitz and Polchinski. We show that the size of the bound state and timescale for formation of a bound state agree at the correspondence point, along with other relevant thermodynamic quantities. The timescale involves matching a parametric resonance in the gauge theory to a quasinormal mode in supergravity. Finally we study construction of local operators in AdS using the generalized AdS/ CFT correspondence. After briefly sketching previous works on this topic which involve massless and massive scalar fields, we present similar construction for spin- 1 and spin- 2 gauge fields. Working in holographic gauge in the bulk, at leading order in 1/N bulk gauge fields are obtained by smearing boundary currents over a sphere on the complexified boundary, while linearized metric fluctuations are obtained by smearing the boundary stress tensor over a ball. This representation respects AdS covariance up to a compensating
Palatini-Born-Infeld gravity, bouncing universe, and black hole formation
NASA Astrophysics Data System (ADS)
Komada, Meguru; Nojiri, Shin'ichi; Katsuragawa, Taishi
2016-04-01
We consider the Palatini formalism of the Born-Infeld gravity. In the Palatini formalism, the propagating mode is only graviton, whose situation is different from that in the metric formalism. We discuss the FRW cosmology by using an effective potential. Especially we consider the condition that the bouncing could occur. We also give some speculations about the black hole formation
Waveforms in massive gravity and neutralization of giant black hole ringings
NASA Astrophysics Data System (ADS)
Décanini, Yves; Folacci, Antoine; Ould El Hadj, Mohamed
2016-06-01
A distorted black hole radiates gravitational waves in order to settle down in a smoother geometry. During that relaxation phase, a characteristic damped ringing is generated. It can be theoretically constructed from both the black hole quasinormal frequencies (which govern its oscillating behavior and its decay) and the associated excitation factors (which determine intrinsically its amplitude) by carefully taking into account the source of the distortion. In the framework of massive gravity, the excitation factors of the Schwarzschild black hole have an unexpected strong resonant behavior which, theoretically, could lead to giant and slowly decaying ringings. If massive gravity is relevant to physics, one can hope to observe these extraordinary ringings by using the next generations of gravitational wave detectors. Indeed, they could be generated by supermassive black holes if the graviton mass is not too small. In fact, by focusing on the odd-parity ℓ=1 mode of the Fierz-Pauli field, we shall show here that such ringings are neutralized in waveforms due to (i) the excitation of the quasibound states of the black hole and (ii) the evanescent nature of the particular partial modes which could excite the concerned quasinormal modes. Despite this, with observational consequences in mind, it is interesting to note that the waveform amplitude is nevertheless rather pronounced and slowly decaying (this effect is now due to the long-lived quasibound states). It is worth noting also that, for very low values of the graviton mass (corresponding to the weak instability regime for the black hole), the waveform is now very clean and dominated by an ordinary ringing which could be used as a signature of massive gravity.
NASA Astrophysics Data System (ADS)
He, Xiao-Gang; Ma, Bo-Qiang
We show that black holes can be quantized in an intuitive and elegant way with results in agreement with conventional knowledge of black holes by using Bohr's idea of quantizing the motion of an electron inside the atom in quantum mechanics. We find that properties of black holes can also be derived from an ansatz of quantized entropy Δ S = 4π k Δ R/{{-{λ }}}, which was suggested in a previous work to unify the black hole entropy formula and Verlinde's conjecture to explain gravity as an entropic force. Such an Ansatz also explains gravity as an entropic force from quantum effect. This suggests a way to unify gravity with quantum theory. Several interesting and surprising results of black holes are given from which we predict the existence of primordial black holes ranging from Planck scale both in size and energy to big ones in size but with low energy behaviors.
Three-dimensional black holes, gravitational solitons, kinks and wormholes for BHT massive gravity
NASA Astrophysics Data System (ADS)
Oliva, Julio; Tempo, David; Troncoso, Ricardo
2009-07-01
The theory of massive gravity in three dimensions recently proposed by Bergshoeff, Hohm and Townsend (BHT) is considered. At the special case when the theory admits a unique maximally symmetric solution, a conformally flat solution that contains black holes and gravitational solitons for any value of the cosmological constant is found. For negative cosmological constant, the black hole is characterized in terms of the mass and the ``gravitational hair'' parameter, providing a lower bound for the mass. For negative mass parameter, the black hole acquires an inner horizon, and the entropy vanishes at the extremal case. Gravitational solitons and kinks, being regular everywhere, can be obtained from a double Wick rotation of the black hole. A wormhole solution in vacuum that interpolates between two static universes of negative spatial curvature is obtained as a limiting case of the gravitational soliton with a suitable identification. The black hole and the gravitational soliton fit within a set of relaxed asymptotically AdS conditions as compared with the one of Brown and Henneaux. In the case of positive cosmological constant the black hole possesses an event and a cosmological horizon, whose mass is bounded from above. Remarkably, the temperatures of the event and the cosmological horizons coincide, and at the extremal case one obtains the analogue of the Nariai solution, dS2 × S1. A gravitational soliton is also obtained through a double Wick rotation of the black hole. The Euclidean continuation of these solutions describes instantons with vanishing Euclidean action. For vanishing cosmological constant the black hole and the gravitational soliton are asymptotically locally flat spacetimes. The rotating solutions can be obtained by boosting the previous ones in the t-phi plane.
Black holes with scalar hair in Einstein-Gauss-Bonnet gravity
NASA Astrophysics Data System (ADS)
Brihaye, Y.; Ducobu, L.
2016-05-01
The Einstein-Gauss-Bonnet gravity in five dimensions is extended by scalar fields and the corresponding equations are reduced to a system of nonlinear differential equations. A large family of regular solutions of these equations is shown to exist. Generically, these solutions are spinning black holes with scalar hairs. They can be characterized (but not uniquely) by an horizon and an angular velocity on this horizon. Taking particular limits, the black holes approach boson star or become extremal, in any case the limiting configurations remain hairy.
Applicability of the Newman-Janis algorithm to black hole solutions of modified gravity theories
NASA Astrophysics Data System (ADS)
Hansen, Devin; Yunes, Nicolás
2013-11-01
The Newman-Janis algorithm has been widely used to construct rotating black hole solutions from nonrotating counterparts. While this algorithm was developed within general relativity (GR), it has more recently been applied to nonrotating solutions in modified gravity theories. We find that the application of the Newman-Janis algorithm to an arbitrary non-GR spherically symmetric solution introduces pathologies in the resulting axially symmetric metric. This then establishes that, in general, the Newman-Janis algorithm should not be used to construct rotating black hole solutions outside of General Relativity.
Daniel Heineman Prize: QCD, strings and black holes: A duality between gravity and field theory
NASA Astrophysics Data System (ADS)
Maldacena, Juan
2007-04-01
We discuss Yang Mills theory with a large number of colors. In this limit it becomes a theory of strings. We describe the string theory associated to the most supersymmetric version of Yang Mills theory. These strings live in a ten dimensional curved space. Thus supersymmetric Yang Mills theory is related to the ordinary ten dimensional superstring theory which describes quantum gravity. We will review some results in this area and discuss some recent developments. We will also discuss the implications for black hole entropy and the black hole information puzzle.
Traversable wormholes and non-singular black holes from the vacuum of quadratic gravity
NASA Astrophysics Data System (ADS)
Duplessis, Francis; Easson, Damien A.
2015-08-01
We present new traversable wormhole and nonsingular black hole solutions in pure, scale-free R2 gravity. These exotic solutions require no null energy condition violating or "exotic" matter and are supported only by the vacuum of the theory. It is well known that f (R ) theories of gravity may be recast as dual theories in the Einstein frame. The solutions we present are found when the conformal transformation required to move to the dual frame is singular. For quadratic R2 gravity, the required conformal factor is identically zero for spacetimes with R =0 . Solutions in this case are argued to arise in the strong coupling limit of general relativity.
- criticality of topological black holes in Lovelock-Born-Infeld gravity
NASA Astrophysics Data System (ADS)
Mo, Jie-Xiong; Liu, Wen-Biao
2014-04-01
To understand the effect of third order Lovelock gravity, - criticality of topological AdS black holes in Lovelock-Born-Infeld gravity is investigated. The thermodynamics is further explored with some more extensions and in some more detail than the previous literature. A detailed analysis of the limit case is performed for the seven-dimensional black holes. It is shown that, for the spherical topology, - criticality exists for both the uncharged and the charged cases. Our results demonstrate again that the charge is not the indispensable condition of - criticality. It may be attributed to the effect of higher derivative terms of the curvature because similar phenomenon was also found for Gauss-Bonnet black holes. For , there would be no - criticality. Interesting findings occur in the case , in which positive solutions of critical points are found for both the uncharged and the charged cases. However, the - diagram is quite strange. To check whether these findings are physical, we give the analysis on the non-negative definiteness condition of the entropy. It is shown that, for any nontrivial value of , the entropy is always positive for any specific volume . Since no - criticality exists for in Einstein gravity and Gauss-Bonnet gravity, we can relate our findings with the peculiar property of third order Lovelock gravity. The entropy in third order Lovelock gravity consists of extra terms which are absent in the Gauss-Bonnet black holes, which makes the critical points satisfy the constraint of non-negative definiteness condition of the entropy. We also check the Gibbs free energy graph and "swallow tail" behavior can be observed. Moreover, the effect of nonlinear electrodynamics is also included in our research.
NASA Astrophysics Data System (ADS)
Luminet, Jean-Pierre
1992-09-01
Foreword to the French edition; Foreword to the English edition; Acknowledgements; Part I. Gravitation and Light: 1. First fruits; 2. Relativity; 3. Curved space-time; Part II. Exquisite Corpses: 4. Chronicle of the twilight years; 5. Ashes and diamonds; 6. Supernovae; 7. Pulsars; 8. Gravitation triumphant; Part III. Light Assassinated: 9. The far horizon; 10. Illuminations; 11. A descent into the maelstrom; 12. Map games; 13. The black hole machine; 14. The quantum black hole; Part IV. Light Regained: 15. Primordial black holes; 16. The zoo of X-ray stars; 17. Giant black holes; 18. Gravitational light; 19. The black hole Universe; Appendices; Bibliography; Name index; Subject index.
(Anti-) de Sitter electrically charged black-hole solutions in higher-derivative gravity
NASA Astrophysics Data System (ADS)
Lin, Kai; Qian, Wei-Liang; Pavan, A. B.; Abdalla, E.
2016-06-01
In this paper, static electrically charged black-hole solutions with cosmological constant are investigated in an Einstein-Hilbert theory of gravity with additional quadratic curvature terms. Beside the analytic Schwarzschild (Anti-) de Sitter solutions, non-Schwarzschild (Anti-) de Sitter solutions are also obtained numerically by employing the shooting method. The results show that there exist two groups of asymptotically (Anti-) de Sitter spacetimes for both charged and uncharged black holes. In particular, it was found that for uncharged black holes the first group can be reduced to the Schwarzschild (Anti-) de Sitter solution, while the second group is intrinsically different from a Schwarzschild (Anti-) de Sitter solution even when the charge and the cosmological constant become zero.
Hawking radiation as tunneling from a Vaidya black hole in noncommutative gravity
NASA Astrophysics Data System (ADS)
Mehdipour, S. Hamid
2010-06-01
In the context of a noncommutative model of coordinate coherent states, we present a Schwarzschild-like metric for a Vaidya solution instead of the standard Eddington-Finkelstein metric. This leads to the appearance of an exact (t-r) dependent case of the metric. We analyze the resulting metric in three possible causal structures. In this setup, we find a zero remnant mass in the long-time limit, i.e. an instable black hole remnant. We also study the tunneling process across the quantum horizon of such a Vaidya black hole. The tunneling probability including the time-dependent part is obtained by using the tunneling method proposed by Parikh and Wilczek in terms of the noncommutative parameter σ. After that, we calculate the entropy associated to this noncommutative black hole solution. However, the corrections are fundamentally trifling; one could respect this as a consequence of quantum inspection at the level of semiclassical quantum gravity.
Stability of warped AdS3 black holes in topologically massive gravity under scalar perturbations
NASA Astrophysics Data System (ADS)
Ferreira, Hugo R. C.
2013-06-01
We demonstrate that the warped AdS3 black hole solutions of topologically massive gravity are classically stable against massive scalar field perturbations by analyzing the quasinormal and bound state modes of the scalar field. In particular, it is found that although classical superradiance is present it does not give rise to superradiant instabilities. The stability is shown to persist even when the black hole is enclosed by a stationary mirror with Dirichlet boundary conditions. This is a surprising result in view of the similarity between the causal structure of the warped AdS3 black hole and the Kerr spacetime in 3+1 dimensions. This work provides the foundations for the study of quantum field theory in this spacetime.
Hawking radiation as tunneling from a Vaidya black hole in noncommutative gravity
Mehdipour, S. Hamid
2010-06-15
In the context of a noncommutative model of coordinate coherent states, we present a Schwarzschild-like metric for a Vaidya solution instead of the standard Eddington-Finkelstein metric. This leads to the appearance of an exact (t-r) dependent case of the metric. We analyze the resulting metric in three possible causal structures. In this setup, we find a zero remnant mass in the long-time limit, i.e. an instable black hole remnant. We also study the tunneling process across the quantum horizon of such a Vaidya black hole. The tunneling probability including the time-dependent part is obtained by using the tunneling method proposed by Parikh and Wilczek in terms of the noncommutative parameter {sigma}. After that, we calculate the entropy associated to this noncommutative black hole solution. However, the corrections are fundamentally trifling; one could respect this as a consequence of quantum inspection at the level of semiclassical quantum gravity.
Regular black holes in f (R ) gravity coupled to nonlinear electrodynamics
NASA Astrophysics Data System (ADS)
Rodrigues, Manuel E.; Junior, Ednaldo L. B.; Marques, Glauber T.; Zanchin, Vilson T.
2016-07-01
We obtain a class of regular black hole solutions in four-dimensional f (R ) gravity, R being the curvature scalar, coupled to a nonlinear electromagnetic source. The metric formalism is used and static spherically symmetric spacetimes are assumed. The resulting f (R ) and nonlinear electrodynamics functions are characterized by a one-parameter family of solutions which are generalizations of known regular black holes in general relativity coupled to nonlinear electrodynamics. The related regular black holes of general relativity are recovered when the free parameter vanishes, in which case one has f (R )∝R . We analyze the regularity of the solutions and also show that there are particular solutions that violate only the strong energy condition.
Slowly-Rotating Black Hole Solution in Einstein-Dilaton-Gauss-Bonnet Gravity
NASA Astrophysics Data System (ADS)
Ayzenberg, Dimitry; Yunes, Nicolas
2015-04-01
We present a stationary and axisymmetric black hole solution in Einstein-Dilaton-Gauss-Bonnet gravity to quadratic order in the ratio of the spin angular momentum to the black hole mass squared. This solution introduces new corrections to previously found nonspinning and linear-in-spin solutions. The location of the event horizon and the ergosphere are modified, as well as the quadrupole moment. The new solution is of Petrov type I, although lower order in spin solutions are of Petrov type D. There are no closed timelike curves or spacetime regions that violate causality outside of the event horizon in the new solution. We calculate the modifications to the binding energy, Kepler's third law, and properties of the innermost stable circular orbit. These modifications are important for determining how the electromagnetic properties of accretion disks around supermassive black holes are changed from those expected in general relativity.
Covariant anomaly and Hawking radiation from the modified black hole in the rainbow gravity theory
NASA Astrophysics Data System (ADS)
Peng, Jun-Jin; Wu, Shuang-Qing
2008-12-01
Recently, Banerjee and Kulkarni (R. Banerjee, S. Kulkarni, arXiv: 0707. 2449 [hep-th]) suggested that it is conceptually clean and economical to use only the covariant anomaly to derive Hawking radiation from a black hole. Based upon this simplified formalism, we apply the covariant anomaly cancellation method to investigate Hawking radiation from a modified Schwarzschild black hole in the theory of rainbow gravity. Hawking temperature of the gravity’s rainbow black hole is derived from the energy-momentum flux by requiring it to cancel the covariant gravitational anomaly at the horizon. We stress that this temperature is exactly the same as that calculated by the method of cancelling the consistent anomaly.
Gravitational lensing by self-dual black holes in loop quantum gravity
NASA Astrophysics Data System (ADS)
Sahu, Satyabrata; Lochan, Kinjalk; Narasimha, D.
2015-03-01
We study gravitational lensing by a recently proposed black hole solution in loop quantum gravity. We highlight the fact that the quantum gravity corrections to the Schwarzschild metric in this model evade the "mass suppression" effects (that the usual quantum gravity corrections are susceptible to) by virtue of one of the parameters in the model being dimensionless, which is unlike any other quantum gravity motivated parameter. Gravitational lensing in the strong and weak deflection regimes is studied, and a sample consistency relation is presented which could serve as a test of this model. We discuss that, though the consistency relation for this model is qualitatively similar to what would have been in Brans-Dicke, in general it can be a good discriminator between many alternative theories. Although the observational prospects do not seem to be very optimistic even for a galactic supermassive black hole case, time delay between relativistic images for a billion solar mass black holes in other galaxies might be within reach of future relativistic lensing observations.
NASA Astrophysics Data System (ADS)
Stein, Leo C.
2014-08-01
Rapidly rotating black holes are a prime arena for understanding corrections to Einstein's theory of general relativity (GR). We construct solutions for rapidly rotating black holes in dynamical Chern-Simons (dCS) gravity, a useful and motivated example of a post-GR correction. We treat dCS as an effective theory and thus work in the decoupling limit, where we apply a perturbation scheme using the Kerr metric as the background solution. Using the solutions to the scalar field and the trace of the metric perturbation, we determine the regime of validity of our perturbative approach. We find that the maximal spin limit may be divergent, and the decoupling limit is strongly restricted for rapid rotation. Rapidly rotating stellar-mass black holes can potentially be used to place strong bounds on the coupling parameter ℓ of dCS. In order for the black hole observed in GRO J1655-40 to be within the decoupling limit, we need ℓ≲22 km, a value 7 orders of magnitude smaller than present Solar System bounds on dynamical Chern-Simons gravity.
NUT-charged black holes in Gauss-Bonnet gravity
Dehghani, M.H.; Mann, R.B.
2005-12-15
We investigate the existence of Taub-NUT (Newman-Unti-Tamburino) and Taub-bolt solutions in Gauss-Bonnet gravity and obtain the general form of these solutions in d dimensions. We find that for all nonextremal NUT solutions of Einstein gravity having no curvature singularity at r=N, there exist NUT solutions in Gauss-Bonnet gravity that contain these solutions in the limit that the Gauss-Bonnet parameter {alpha} goes to zero. Furthermore there are no NUT solutions in Gauss-Bonnet gravity that yield nonextremal NUT solutions to Einstein gravity having a curvature singularity at r=N in the limit {alpha}{yields}0. Indeed, we have nonextreme NUT solutions in 2+2k dimensions with nontrivial fibration only when the 2k-dimensional base space is chosen to be CP{sup 2k}. We also find that the Gauss-Bonnet gravity has extremal NUT solutions whenever the base space is a product of 2-torii with at most a two-dimensional factor space of positive curvature. Indeed, when the base space has at most one positively curved two-dimensional space as one of its factor spaces, then Gauss-Bonnet gravity admits extreme NUT solutions, even though there a curvature singularity exists at r=N. We also find that one can have bolt solutions in Gauss-Bonnet gravity with any base space with factor spaces of zero or positive constant curvature. The only case for which one does not have bolt solutions is in the absence of a cosmological term with zero curvature base space.
Geometrothermodynamics of black holes in Lovelock gravity with a nonlinear electrodynamics
NASA Astrophysics Data System (ADS)
Hendi, S. H.; Naderi, R.
2015-01-01
The objective of the present paper is to analyze the phase transition of asymptotically anti-de Sitter (AdS) black-hole solutions in Lovelock gravity in the presence of nonlinear electrodynamics. First, we present the asymptotically AdS black-hole solutions for two classes of the Born-Infeld type of nonlinear electrodynamics coupled (separately) with Einstein, Gauss-Bonnet, and third-order Lovelock gravity. Then, in order to discuss the phase transition, we calculate both the heat capacity and the Ricci scalar of the thermodynamical line element. We present a comparison between the singular points of the Ricci scalar using the geometrothermodynamics method and the corresponding vanishing points of the heat capacity in the canonical ensemble. In addition, we discuss the effects of both Lovelock and nonlinear electrodynamics on the phase transition points.
Fluid/gravity correspondence for general non-rotating black holes
NASA Astrophysics Data System (ADS)
Wu, Xiaoning; Ling, Yi; Tian, Yu; Zhang, Chengyong
2013-07-01
In this paper, we investigate the fluid/gravity correspondence in spacetime with general non-rotating weakly isolated horizon. With the help of a Petrov-like boundary condition and large mean curvature limit, we show that the dual hydrodynamical system is described by a generalized forced incompressible Navier-Stokes equation. Specially, for stationary black holes or those spacetime with some asymptotically stationary conditions, such a system reduces to a standard forced Navier-Stokes system.
The string landscape, black holes and gravity as the weakest force
NASA Astrophysics Data System (ADS)
Arkani-Hamed, Nima; Motl, Luboš; Nicolis, Alberto; Vafa, Cumrun
2007-06-01
We conjecture a general upper bound on the strength of gravity relative to gauge forces in quantum gravity. This implies, in particular, that in a four-dimensional theory with gravity and a U(1) gauge field with gauge coupling g, there is a new ultraviolet scale Λ = gMPl, invisible to the low-energy effective field theorist, which sets a cutoff on the validity of the effective theory. Moreover, there is some light charged particle with mass smaller than or equal to Λ. The bound is motivated by arguments involving holography and absence of remnants, the (in) stability of black holes as well as the non-existence of global symmetries in string theory. A sharp form of the conjecture is that there are always light ``elementary'' electric and magnetic objects with a mass/charge ratio smaller than the corresponding ratio for macroscopic extremal black holes, allowing extremal black holes to decay. This conjecture is supported by a number of non-trivial examples in string theory. It implies the necessary presence of new physics beneath the Planck scale, not far from the GUT scale, and explains why some apparently natural models of inflation resist an embedding in string theory.
NASA Astrophysics Data System (ADS)
Setare, M. R.; Adami, H.
2016-09-01
We consider the Generalized Minimal Massive Gravity (GMMG) model in the first order formalism. We show that all the solutions of the Einstein gravity with negative cosmological constants solve the equations of motion of considered model. Then we find an expression for the off-shell conserved charges of this model. By considering the near horizon geometry of a three dimensional black hole in the Gaussian null coordinates, we find near horizon conserved charges and their algebra. The obtained algebra is centrally extended. By writing the algebra of conserved charges in terms of Fourier modes and considering the BTZ black hole solution as an example, one can see that the charge associated with rotations along Y0 coincides exactly with the angular momentum, and the charge associated with time translations T0 is the product of the black hole entropy and its temperature. As we expect, in the limit when the GMMG tends to the Einstein gravity, all the results we obtain in this paper reduce to the results of the paper [1].
Planar AdS black holes in Lovelock gravity with a nonminimal scalar field
NASA Astrophysics Data System (ADS)
Gaete, Moisés Bravo; Hassaïne, Mokhtar
2013-11-01
In arbitrary dimension D, we consider a self-interacting scalar field nonminimally coupled with a gravity theory given by a particular Lovelock action indexed by an integer k. To be more precise, the coefficients appearing in the Lovelock expansion are fixed by requiring the theory to have a unique AdS vacuum with a fixed value of the cosmological constant. This yields to k = 1, 2,⋯, inequivalent possible gravity theories; here the case k = 1 corresponds to the standard Einstein-Hilbert Lagrangian. For each par ( D, k), we derive two classes of AdS black hole solutions with planar event horizon topology for particular values of the nonminimal coupling parameter. The first family of solutions depends on a unique constant and is valid only for k ≥ 2. In fact, its GR counterpart k = 1 reduces to the pure AdS metric with a vanishing scalar field. The second family of solutions involves two independent constants and corresponds to a stealth black hole configuration; that is a nontrivial scalar field together with a black hole metric such that both side of the Einstein equations (gravity and matter parts) vanishes identically. In this case, the standard GR case k = 1 reduces to the Schwarzschild-AdS-Tangherlini black hole metric with a trivial scalar field. We show that the two-parametric stealth solution defined in D dimension can be promoted to the uniparametric black hole solution in ( D + 1) dimension by fixing one of the two constants in term of the other and by adding a transversal coordinate. In both cases, the existence of these solutions is strongly inherent of the presence of the higher order curvature terms k ≥ 2 of the Lovelock gravity. We also establish that these solutions emerge from a stealth configuration defined on the pure AdS metric through a Kerr-Schild transformation. Finally, in the last part, we include multiple exact ( D - 1) - forms homogenously distributed and coupled to the scalar field. For a specific coupling, we obtain black hole
Space, time, and gravity - The theory of the big bang and black holes (2nd edition)
NASA Astrophysics Data System (ADS)
Wald, Robert M.
An elementary introduction to modern cosmology for general readers is presented. The topics addressed include: the geometry of space and time, special and general relativity, the big bang, the evolution of the universe, stellar evolution, gravitational collapse to black holes, energy extraction from black holes, the astrophysics of black holes, and quantum particle creation near black holes.
Black holes in an asymptotically safe gravity theory with higher derivatives
Cai, Yi-Fu; Easson, Damien A. E-mail: easson@asu.edu
2010-09-01
We present a class of spherically symmetric vacuum solutions to an asymptotically safe theory of gravity containing high-derivative terms. We find quantum corrected Schwarzschild-(anti)-de Sitter solutions with running gravitational coupling parameters. The evolution of the couplings is determined by their corresponding renormalization group flow equations. These black holes exhibit properties of a classical Schwarzschild solution at large length scales. At the center, the metric factor remains smooth but the curvature singularity, while softened by the quantum corrections, persists. The solutions have an outer event horizon and an inner Cauchy horizon which equate when the physical mass decreases to a critical value. Super-extremal solutions with masses below the critical value correspond to naked singularities. The Hawking temperature of the black hole vanishes when the physical mass reaches the critical value. Hence, the black holes in the asymptotically safe gravitational theory never completely evaporate. For appropriate values of the parameters such stable black hole remnants make excellent dark matter candidates.
NASA Astrophysics Data System (ADS)
Chakraborty, Sumanta
2015-04-01
The hydrodynamic behavior of perfect fluid orbiting around black holes in spherically symmetric spacetime for various alternative gravity theories has been investigated. For this purpose we have assumed a uniform distribution for the angular momentum density of the rotating perfect fluid. The contours of equipotential surfaces are illustrated in order to obtain the nature of inflow and outflow of matter. It has been noticed that the marginally stable circular orbits originating from decreasing angular momentum density lead to closed equipotential surfaces along with cusps, allowing the existence of accretion disks. On the other hand, the growing part of the angular momentum density exhibits central rings for which stable configurations are possible. However, inflow of matter is prohibited. Among the solutions discussed in this work, the charged F(R) gravity and Einstein-Maxwell-Gauss-Bonnet solutions exhibit inflow and outflow of matter with central rings present. These varied accretion disk structures of perfect fluid attribute astrophysical importance to these spacetimes. The effect of higher curvature terms predominantly arises from the region near the black hole horizon. Hence the structural difference of the accretion disk in modified gravity theories in comparison to general relativity may act as an experimental probe for these alternative gravity theories.
Self-dual black holes in loop quantum gravity: Theory and phenomenology
Modesto, Leonardo; Premont-Schwarz, Isabeau
2009-09-15
In this paper we have recalled the semiclassical metric obtained from a classical analysis of the loop quantum black hole (LQBH). We show that the regular Reissner-Nordstroem-like metric is self-dual in the sense of T-duality: the form of the metric obtained in loop quantum gravity is invariant under the exchange r{yields}a{sub 0}/r where a{sub 0} is proportional to the minimum area in loop quantum gravity and r is the standard Schwarzschild radial coordinate at asymptotic infinity. Of particular interest, the symmetry imposes that if an observer in r{yields}+{infinity} sees a black hole of mass m an observer in the other asymptotic infinity beyond the horizon (at r{approx_equal}0) sees a dual mass m{sub P}/m. We then show that small LQBH are stable and could be a component of dark matter. Ultralight LQBHs created shortly after the big bang would now have a mass of approximately 10{sup -5}m{sub P} and emit radiation with a typical energy of about 10{sup 13}-10{sup 14} eV but they would also emit cosmic rays of much higher energies, albeit few of them. If these small LQBHs form a majority of the dark matter of the Milky Way's Halo, the production rate of ultra-high-energy-cosmic-rays (UHECR) by these ultralight black holes would be compatible with the observed rate of the Auger detector.
NASA Astrophysics Data System (ADS)
Hendi, S. H.; Panahiyan, S.
2014-12-01
Motivated by the string corrections on the gravity and electrodynamics sides, we consider a quadratic Maxwell invariant term as a correction of the Maxwell Lagrangian to obtain exact solutions of higher dimensional topological black holes in Gauss-Bonnet gravity. We first investigate the asymptotically flat solutions and obtain conserved and thermodynamic quantities which satisfy the first law of thermodynamics. We also analyze thermodynamic stability of the solutions by calculating the heat capacity and the Hessian matrix. Then, we focus on horizon-flat solutions with an anti-de Sitter (AdS) asymptote and produce a rotating spacetime with a suitable transformation. In addition, we calculate the conserved and thermodynamic quantities for asymptotically AdS black branes which satisfy the first law of thermodynamics. Finally, we perform thermodynamic instability criterion to investigate the effects of nonlinear electrodynamics in canonical and grand canonical ensembles.
Gravitational signature of Schwarzschild black holes in dynamical Chern-Simons gravity
Molina, C.; Pani, Paolo; Cardoso, Vitor; Gualtieri, Leonardo
2010-06-15
Dynamical Chern-Simons gravity is an extension of general relativity in which the gravitational field is coupled to a scalar field through a parity-violating Chern-Simons term. In this framework, we study perturbations of spherically symmetric black hole spacetimes, assuming that the background scalar field vanishes. Our results suggest that these spacetimes are stable, and small perturbations die away as a ringdown. However, in contrast to standard general relativity, the gravitational waveforms are also driven by the scalar field. Thus, the gravitational oscillation modes of black holes carry imprints of the coupling to the scalar field. This is a smoking gun for Chern-Simons theory and could be tested with gravitational-wave detectors, such as LIGO or LISA. For negative values of the coupling constant, ghosts are known to arise, and we explicitly verify their appearance numerically. Our results are validated using both time evolution and frequency domain methods.
Finsler black holes induced by noncommutative anholonomic distributions in Einstein gravity
NASA Astrophysics Data System (ADS)
Vacaru, Sergiu I.
2010-05-01
We study Finsler black holes induced from Einstein gravity as possible effects of quantum spacetime noncommutativity. Such Finsler models are defined by nonholonomic frames not on tangent bundles but on (pseudo)Riemannian manifolds being compatible with standard theories of physics. We focus on noncommutative deformations of Schwarzschild metrics into locally anisotropic stationary ones with spherical/rotoid symmetry. The conditions are derived when black hole configurations can be extracted from two classes of exact solutions depending on noncommutative parameters. The first class of metrics is defined by nonholonomic deformations of the gravitational vacuum by noncommutative geometry. The second class of such solutions is induced by noncommutative matter fields and/or effective polarizations of cosmological constants.
Gravitational signature of Schwarzschild black holes in dynamical Chern-Simons gravity
NASA Astrophysics Data System (ADS)
Molina, C.; Pani, Paolo; Cardoso, Vitor; Gualtieri, Leonardo
2010-06-01
Dynamical Chern-Simons gravity is an extension of general relativity in which the gravitational field is coupled to a scalar field through a parity-violating Chern-Simons term. In this framework, we study perturbations of spherically symmetric black hole spacetimes, assuming that the background scalar field vanishes. Our results suggest that these spacetimes are stable, and small perturbations die away as a ringdown. However, in contrast to standard general relativity, the gravitational waveforms are also driven by the scalar field. Thus, the gravitational oscillation modes of black holes carry imprints of the coupling to the scalar field. This is a smoking gun for Chern-Simons theory and could be tested with gravitational-wave detectors, such as LIGO or LISA. For negative values of the coupling constant, ghosts are known to arise, and we explicitly verify their appearance numerically. Our results are validated using both time evolution and frequency domain methods.
Critical behavior of charged black holes in Gauss-Bonnet gravity's rainbow
NASA Astrophysics Data System (ADS)
Hendi, Seyed Hossein; Panahiyan, Shahram; Eslam Panah, Behzad; Faizal, Mir; Momennia, Mehrab
2016-07-01
Following an earlier study regarding Gauss-Bonnet-Maxwell black holes in the presence of gravity's rainbow [S. H. Hendi and M. Faizal, Phys. Rev. D 92, 044027 (2015)], in this paper, we consider all constants as energy dependent ones. The geometrical and thermodynamical properties of this generalization is studied and the validation of the first law of thermodynamics is examined. Next, through the use of proportionality between the cosmological constant and the thermodynamical pressure, van der Waals-like behavior of these black holes in extended phase space is investigated. An interesting critical behavior for sets of rainbow functions in this case is reported. Also, the critical behavior of uncharged and charged solutions is analyzed and it is shown that the generalization to a charged case puts an energy dependent restriction on values of different parameters.
Reissner–Nordström Anti-de Sitter Black Holes in Mimetic F(R) Gravity
NASA Astrophysics Data System (ADS)
Oikonomou, V. K.
2016-05-01
In this paper we study under which conditions the Reissner-Nordstr\\"om-anti de Sitter black hole can be a solution of the vacuum mimetic $F(R)$ gravity with Lagrange multiplier and mimetic scalar potential. As we demonstrate, the resulting picture in the mimetic $F(R)$ gravity case, is different in comparison to the ordinary $F(R)$ gravity case, with the two descriptions resulting to a different set of constraints that need to hold true. We also investigate the metric perturbations in the mimetic $F(R)$ gravity case, for the Reissner-Nordstr\\"om-anti de Sitter black hole metric, at first order of the perturbed variables. Interestingly enough, the resulting equations are identical to the ones corresponding to the ordinary $F(R)$ gravity Reissner-Nordstr\\"om-anti de Sitter black hole, at least at first order. We attribute this feature to the particular form of the Reissner-Nordstr\\"om-anti de Sitter metric, and we speculate for which cases there could be differences between the mimetic and non-mimetic case. Since the perturbation equations are the same for the two cases, it is possible to have black hole instabilities in the mimetic $F(R)$ gravity case too, which can be interpreted as anti-evaporation of the black hole.
Gravitational waves from quasicircular black-hole binaries in dynamical Chern-Simons gravity.
Yagi, Kent; Yunes, Nicolás; Tanaka, Takahiro
2012-12-21
Dynamical Chern-Simons gravity cannot be strongly constrained with current experiments because it reduces to general relativity in the weak-field limit. This theory, however, introduces modifications in the nonlinear, dynamical regime, and thus it could be greatly constrained with gravitational waves from the late inspiral of black-hole binaries. We complete the first self-consistent calculation of such gravitational waves in this theory. For favorable spin orientations, advanced ground-based detectors may improve existing solar system constraints by 6 orders of magnitude. PMID:23368447
General parametrization of axisymmetric black holes in metric theories of gravity
NASA Astrophysics Data System (ADS)
Konoplya, Roman; Rezzolla, Luciano; Zhidenko, Alexander
2016-03-01
Following previous work of ours in spherical symmetry, we here propose a new parametric framework to describe the spacetime of axisymmetric black holes in generic metric theories of gravity. In this case, the metric components are functions of both the radial and the polar angular coordinates, forcing a double expansion to obtain a generic axisymmetric metric expression. In particular, we use a continued-fraction expansion in terms of a compactified radial coordinate to express the radial dependence, while we exploit a Taylor expansion in terms of the cosine of the polar angle for the polar dependence. These choices lead to a superior convergence in the radial direction and to an exact limit on the equatorial plane. As a validation of our approach, we build parametrized representations of Kerr, rotating dilaton, and Einstein-dilaton-Gauss-Bonnet black holes. The match is already very good at lowest order in the expansion and improves as new orders are added. We expect a similar behavior for any stationary and axisymmetric black-hole metric.
Mathur, Samir D.
2012-11-15
The black hole information paradox forces us into a strange situation: we must find a way to break the semiclassical approximation in a domain where no quantum gravity effects would normally be expected. Traditional quantizations of gravity do not exhibit any such breakdown, and this forces us into a difficult corner: either we must give up quantum mechanics or we must accept the existence of troublesome 'remnants'. In string theory, however, the fundamental quanta are extended objects, and it turns out that the bound states of such objects acquire a size that grows with the number of quanta in the bound state. The interior of the black hole gets completely altered to a 'fuzzball' structure, and information is able to escape in radiation from the hole. The semiclassical approximation can break at macroscopic scales due to the large entropy of the hole: the measure in the path integral competes with the classical action, instead of giving a subleading correction. Putting this picture of black hole microstates together with ideas about entangled states leads to a natural set of conjectures on many long-standing questions in gravity: the significance of Rindler and de Sitter entropies, the notion of black hole complementarity, and the fate of an observer falling into a black hole. - Highlights: Black-Right-Pointing-Pointer The information paradox is a serious problem. Black-Right-Pointing-Pointer To solve it we need to find 'hair' on black holes. Black-Right-Pointing-Pointer In string theory we find 'hair' by the fuzzball construction. Black-Right-Pointing-Pointer Fuzzballs help to resolve many other issues in gravity.
NASA Astrophysics Data System (ADS)
El-Menoufi, Basem Kamal
2016-05-01
In the context of effective field theory, we consider quantum gravity with minimally coupled massless particles. Fixing the background geometry to be of the Kerr-Schild type, we fully determine the one-loop effective action of the theory whose finite non-local part is induced by the long-distance portion of quantum loops. This is accomplished using the non-local expansion of the heat kernel in addition to a non-linear completion technique through which the effective action is expanded in gravitational curvatures. Via Euclidean methods, we identify a logarithmic correction to the Bekenstein-Hawking entropy of Schwarzschild black hole. Using dimensional transmutation the result is shown to exhibit an interesting interplay between the UV and IR properties of quantum gravity.
Taub-NUT/bolt black holes in Gauss-Bonnet-Maxwell gravity
Dehghani, M.H.; Hendi, S. H.
2006-04-15
We present a class of higher-dimensional solutions to Gauss-Bonnet-Maxwell equations in 2k+2 dimensions with a U(1) fibration over a 2k-dimensional base space B. These solutions depend on two extra parameters, other than the mass and the Newman-Unti-Tamburino charge, which are the electric charge q and the electric potential at infinity V. We find that the form of metric is sensitive to geometry of the base space, while the form of electromagnetic field is independent of B. We investigate the existence of Taub-Newman-Unti-Tamburino/bolt solutions and find that in addition to the two conditions of uncharged Newman-Unti-Tamburino solutions, there exist two other conditions. These two extra conditions come from the regularity of vector potential at r=N and the fact that the horizon at r=N should be the outer horizon of the black hole. We find that for all nonextremal Newman-Unti-Tamburino solutions of Einstein gravity having no curvature singularity at r=N, there exist Newman-Unti-Tamburino solutions in Gauss-Bonnet-Maxwell gravity. Indeed, we have nonextreme Newman-Unti-Tamburino solutions in 2+2k dimensions only when the 2k-dimensional base space is chosen to be CP{sup 2k}. We also find that the Gauss-Bonnet-Maxwell gravity has extremal Newman-Unti-Tamburino solutions whenever the base space is a product of 2-torii with at most a 2-dimensional factor space of positive curvature, even though there a curvature singularity exists at r=N. We also find that one can have bolt solutions in Gauss-Bonnet-Maxwell gravity with any base space. The only case for which one does not have black hole solutions is in the absence of a cosmological term with zero curvature base space.
Perturbations of Schwarzschild black holes in Chern-Simons modified gravity
NASA Astrophysics Data System (ADS)
Yunes, Nicolás; Sopuerta, Carlos F.
2008-03-01
We study perturbations of a Schwarzschild black hole in Chern-Simons modified gravity. We begin by showing that Birkhoff’s theorem holds for a wide family of Chern-Simons coupling functions, a scalar field present in the theory that controls the strength of the Chern-Simons correction to the Einstein-Hilbert action. After decomposing the perturbations in spherical harmonics, we study the linearized modified field equations and find that axial and polar modes are coupled, in contrast to general relativity. The divergence of the modified equations leads to the Pontryagin constraint, which forces the vanishing of the Cunningham-Price-Moncrief master function associated with axial modes. We analyze the structure of these equations and find that the appearance of the Pontryagin constraint yields an overconstrained system that does not allow for generic black hole oscillations. We illustrate this situation by studying the case characterized by a canonical choice of the coupling function and pure-parity perturbative modes. We end with a discussion of how to extend Chern-Simons modified gravity to bypass the Pontryagin constraint and the suppression of perturbations.
NASA Astrophysics Data System (ADS)
Zangeneh, M. Kord; Dehyadegari, A.; Sheykhi, A.; Dehghani, M. H.
2016-03-01
In this paper, we construct a new class of topological black hole Lifshitz solutions in the presence of nonlinear exponential electrodynamics for Einstein-dilaton gravity. We show that the reality of Lifshitz supporting Maxwell matter fields exclude the negative horizon curvature solutions except for the asymptotic AdS case. Calculating the conserved and thermodynamical quantities, we obtain a Smarr type formula for the mass and confirm that thermodynamics first law is satisfied on the black hole horizon. Afterward, we study the thermal stability of our solutions and figure out the effects of different parameters on the stability of solutions under thermal perturbations. Next, we apply the gauge/gravity duality in order to calculate the ratio of shear viscosity to entropy for a three-dimensional hydrodynamic system by using the pole method. Furthermore, we study the behavior of holographic conductivity for two-dimensional systems such as graphene. We consider linear Maxwell and nonlinear exponential electrodynamics separately and disclose the effect of nonlinearity on holographic conductivity. We indicate that holographic conductivity vanishes for z > 3 in the case of nonlinear electrodynamics while it does not in the linear Maxwell case. Finally, we solve perturbative additional field equations numerically and plot the behaviors of real and imaginary parts of conductivity for asymptotic AdS and Lifshitz cases. We present experimental results match with our numerical ones.
Einstein-Born-Infeld-massive gravity: adS-black hole solutions and their thermodynamical properties
NASA Astrophysics Data System (ADS)
Hendi, S. H.; Panah, B. Eslam; Panahiyan, S.
2015-11-01
In this paper, we study massive gravity in the presence of Born-Infeld nonlinear electrodynamics. First, we obtain metric function related to this gravity and investigate the geometry of the solutions and find that there is an essential singularity at the origin ( r = 0). It will be shown that due to contribution of the massive part, the number, type and place of horizons may be changed. Next, we calculate the conserved and thermodynamic quantities and check the validation of the first law of thermodynamics. We also investigate thermal stability of these black holes in context of canonical ensemble. It will be shown that number, type and place of phase transition points are functions of different parameters which lead to dependency of stability conditions to these parameters. Also, it will be shown how the behavior of temperature is modified due to extension of massive gravity and strong nonlinearity parameter. Next, critical behavior of the system in extended phase space by considering cosmological constant as pressure is investigated. A study regarding neutral Einstein-massive gravity in context of extended phase space is done. Geometrical approach is employed to study the thermodynamical behavior of the system in context of heat capacity and extended phase space. It will be shown that GTs, heat capacity and extended phase space have consistent results. Finally, critical behavior of the system is investigated through use of another method. It will be pointed out that the results of this method is in agreement with other methods and follow the concepts of ordinary thermodynamics.
Prospects for Probing Strong Gravity with a Pulsar-Black Hole System
NASA Technical Reports Server (NTRS)
Wex, N.; Liu, K.; Eatough, R. P.; Kramer, M.; Cordes, J. M.; Lazio, T. J. W.
2012-01-01
The discovery of a pulsar (PSR) in orbit around a black hole (BH) is expected to provide a superb new probe of relativistic gravity and BH properties. Apart from a precise mass measurement for the BH, one could expect a clean verification of the dragging of space-time caused by the BH spin. In order to measure the quadrupole moment of the BH for testing the no-hair theorem of general relativity (GR), one has to hope for a sufficiently massive BH. In this respect, a PSR orbiting the super-massive BH in the center of our Galaxy would be the ultimate laboratory for gravity tests with PSRs. But even for gravity theories that predict the same properties for BHs as GR, a PSR-BH system would constitute an excellent test system, due to the high grade of asymmetry in the strong field properties of these two components. Here we highlight some of the potential gravity tests that one could expect from different PSR-BH systems.
NASA Astrophysics Data System (ADS)
Sotani, Hajime; Miyamoto, Umpei
2015-08-01
We systematically examine the properties of null geodesics around an electrically charged, asymptotically flat black hole in Eddington-inspired Born-Infeld gravity, varying the electric charge of the black hole and the coupling constant in the theory. We find that the radius of the unstable circular orbit for a massless particle decreases with the coupling constant, if the value of the electrical charge is fixed. Additionally, we consider the strong gravitational lensing around such a black hole. We show that the deflection angle, the position angle of the relativistic images, and the magnification due to the light bending in strong gravitational field are quite sensitive to the parameters determining the black hole solution. Thus, through the accurate observations associated with the strong gravitational lensing, it might be possible to reveal the gravitational theory in a strong field regime.
Two aspects of black hole entropy in Lanczos-Lovelock models of gravity
NASA Astrophysics Data System (ADS)
Kolekar, Sanved; Kothawala, Dawood; Padmanabhan, T.
2012-03-01
We consider two specific approaches to evaluate the black hole entropy which are known to produce correct results in the case of Einstein’s theory and generalize them to Lanczos-Lovelock models. In the first approach (which could be called extrinsic), we use a procedure motivated by earlier work by Pretorius, Vollick, and Israel, and by Oppenheim, and evaluate the entropy of a configuration of densely packed gravitating shells on the verge of forming a black hole in Lanczos-Lovelock theories of gravity. We find that this matter entropy is not equal to (it is less than) Wald entropy, except in the case of Einstein theory, where they are equal. The matter entropy is proportional to the Wald entropy if we consider a specific mth-order Lanczos-Lovelock model, with the proportionality constant depending on the spacetime dimensions D and the order m of the Lanczos-Lovelock theory as (D-2m)/(D-2). Since the proportionality constant depends on m, the proportionality between matter entropy and Wald entropy breaks down when we consider a sum of Lanczos-Lovelock actions involving different m. In the second approach (which could be called intrinsic), we generalize a procedure, previously introduced by Padmanabhan in the context of general relativity, to study off-shell entropy of a class of metrics with horizon using a path integral method. We consider the Euclidean action of Lanczos-Lovelock models for a class of metrics off shell and interpret it as a partition function. We show that in the case of spherically symmetric metrics, one can interpret the Euclidean action as the free energy and read off both the entropy and energy of a black hole spacetime. Surprisingly enough, this leads to exactly the Wald entropy and the energy of the spacetime in Lanczos-Lovelock models obtained by other methods. We comment on possible implications of the result.
5D radiating black holes in Einstein-Yang-Mills-Gauss-Bonnet gravity
NASA Astrophysics Data System (ADS)
Ghosh, S. G.
2011-10-01
We derive nonstatic spherically symmetric solutions of a null fluid, in five dimension (5D), to Einstein-Yang-Mills (EYM) equations with the coupling of Gauss-Bonnet (GB) combination of quadratic curvature terms, namely, 5D EYMGB radiating black hole solution. It is shown that, in the limit, we can recover known radiating black hole solutions. The spherically symmetric known 5D static black hole solutions are also retrieved. The effect of the GB term and Yang-Mills (YM) gauge charge on the structure and location of horizons, of the 5D radiating black hole, is also discussed.
NASA Astrophysics Data System (ADS)
Hartman, Thomas Edward
The connection between black holes in four dimensions and conformal field theories (CFTs) in two dimensions is explored, focusing on zero temperature (extreme) black holes and their low-temperature cousins. It is shown that extreme black holes in a theory of quantum gravity are holographically dual to field theories living in two dimensions without gravity, and that the field theory reproduces a variety of black hole phenomena in detail. The extreme black hole/CFT correspondence is derived from a symmetry analysis near the horizon of a Kerr black hole with mass M and maximal angular momentum J=M 2. The asymptotic symmetry generators form one copy of the Virasoro algebra with central charge c=12J, which implies that the near-horizon quantum states are identical to those of a two-dimensional CFT. We discuss extensions of this result to near-extreme black holes and cosmological horizons. Astrophysical black holes are never exactly extremal, but the black hole GRS1915+105 observed through X-ray and radio telescopy is likely within 1% of the extremal spin, suggesting that this extraordinary and well studied object is approximately dual to a two-dimensional CFT with c˜1079. As evidence for the correspondence, microstate counting in the CFT is used to derive the Bekenstein-Hawking area law for the Kerr entropy, S=Horizon area/4. Furthermore, the correlators in the dual CFT are shown to reproduce the scattering amplitudes of a charged scalar or spin-½ field by a near-extreme Kerr-Newman black hole, and a neutral spin-1 or spin-2 field by a near-extreme Kerr black hole. Scattering amplitudes probe the vacuum of fields living on the black hole background. For scalars, bound superradiant modes lead to an instability, while for fermions, it is shown that the bound superradiant modes condense and form a Fermi sea which extends well outside the ergosphere. Assuming no further instabilities, the low energy effective theory near the black hole is described by ripples in the
Generalisation for regular black holes on general relativity to f( R) gravity
NASA Astrophysics Data System (ADS)
Rodrigues, Manuel E.; Fabris, Júlio C.; Junior, Ednaldo L. B.; Marques, Glauber T.
2016-05-01
In this paper, we determine regular black hole solutions using a very general f( R) theory, coupled to a non-linear electromagnetic field given by a Lagrangian {L}_NED. The functions f( R) and {L}_NED are in principle left unspecified. Instead, the model is constructed through a choice of the mass function M( r) presented in the metric coefficients. Solutions which have a regular behaviour of the geometric invariants are found. These solutions have two horizons, the event horizon and the Cauchy horizon. All energy conditions are satisfied in the whole space-time, except the strong energy condition (SEC), which is violated near the Cauchy horizon. We present also a new theorem related to the energy conditions in f( R) gravity, re-obtaining the well-known conditions in the context of general relativity when the geometry of the solution is the same.
Thermodynamics of Taub-NUT/bolt-AdS black holes in Einstein-Gauss-Bonnet gravity
Khodam-Mohammadi, A.; Monshizadeh, M.
2009-02-15
We give a review of the existence of Taub-NUT/bolt solutions in Einstein Gauss-Bonnet gravity with the parameter {alpha} in six dimensions. Although the spacetime with base space S{sup 2}xS{sup 2} has a curvature singularity at r=N, which does not admit NUT solutions, we may proceed with the same computations as in the CP{sup 2} case. The investigation of thermodynamics of NUT/bolt solutions in six dimensions is carried out. We compute the finite action, mass, entropy, and temperature of the black hole. Then the validity of the first law of thermodynamics is demonstrated. It is shown that in NUT solutions all thermodynamic quantities for both base spaces are related to each other by substituting {alpha}{sup CP{sup k}}=[(k+1)/k]{alpha}{sup S{sup 2}}{sup xS{sup 2}}{sup x...S{sub k}{sup 2}}. So, no further information is given by investigating NUT solutions in the S{sup 2}xS{sup 2} case. This relation is not true for bolt solutions. A generalization of the thermodynamics of black holes to arbitrary even dimensions is made using a new method based on the Gibbs-Duhem relation and Gibbs free energy for NUT solutions. According to this method, the finite action in Einstein Gauss-Bonnet is obtained by considering the generalized finite action in Einstein gravity with an additional term as a function of {alpha}. Stability analysis is done by investigating the heat capacity and entropy in the allowed range of {alpha}, {lambda}, and N. For NUT solutions in d dimensions, there exists a stable phase at a narrow range of {alpha}. In six-dimensional bolt solutions, the metric is completely stable for B=S{sup 2}xS{sup 2} and is completely unstable for the B=CP{sup 2} case.
Black Holes in Higher Dimensions
NASA Astrophysics Data System (ADS)
Horowitz, Gary T.
2012-04-01
List of contributors; Preface; Part I. Introduction: 1. Black holes in four dimensions Gary Horowitz; Part II. Five Dimensional Kaluza-Klein Theory: 2. The Gregory-Laflamme instability Ruth Gregory; 3. Final state of Gregory-Laflamme instability Luis Lehner and Frans Pretorius; 4. General black holes in Kaluza-Klein theory Gary Horowitz and Toby Wiseman; Part III. Higher Dimensional Solutions: 5. Myers-Perry black holes Rob Myers; 6. Black rings Roberto Emparan and Harvey Reall; Part IV. General Properties: 7. Constraints on the topology of higher dimensional black holes Greg Galloway; 8. Blackfolds Roberto Emparan; 9. Algebraically special solutions in higher dimensions Harvey Reall; 10. Numerical construction of static and stationary black holes Toby Wiseman; Part V. Advanced Topics: 11. Black holes and branes in supergravity Don Marolf; 12. The gauge/gravity duality Juan Maldacena; 13. The fluid/gravity correspondence Veronika Hubeny, Mukund Rangamani and Shiraz Minwalla; 14. Horizons, holography and condensed matter Sean Hartnoll; Index.
NASA Astrophysics Data System (ADS)
Vaz, Cenalo; Wijewardhana, L. C. R.
2013-12-01
General consensus on the nature of the degrees of freedom responsible for the black hole entropy remains elusive despite decades of effort dedicated to the problem. Different approaches to quantum gravity disagree in their description of the microstates and, more significantly, in the statistics used to count them. In some approaches (string theory, AdS/CFT) the elementary degrees of freedom are indistinguishable, whereas they must be treated as distinguishable in other approaches to quantum gravity (eg., LQG) in order to recover the Bekenstein-Hawking area-entropy law. However, different statistics will imply different behaviors of the black hole outside the thermodynamic limit. We illustrate this point by quantizing the Bañados-Teitelboim-Zanelli (BTZ) black hole, for which we argue that Bose condensation will occur leading to a "cold", stable remnant.
Quasinormal modes of self-dual warped AdS3 black hole in topological massive gravity
NASA Astrophysics Data System (ADS)
Li, Ran; Ren, Ji-Rong
2011-03-01
We consider the scalar, vector and spinor field perturbations in the background of self-dual warped AdS3 black hole of topological massive gravity. The corresponding exact expressions for quasinormal modes are obtained by analytically solving the perturbation equations and imposing the vanishing Dirichlet boundary condition at asymptotic infinity. It is expected that the quasinormal modes agree with the poles of retarded Green’s functions of the CFT dual to self-dual warped AdS3 black hole. Our results provide a quantitative test of the warped AdS/CFT correspondence.
Thermodynamics of Taub-NUT/bolt black holes in Einstein-Maxwell gravity
Dehghani, M.H.; Khodam-Mohammadi, A.
2006-06-15
First, we construct the Taub-NUT/bolt solutions of (2k+2)-dimensional Einstein-Maxwell gravity, when all the factor spaces of 2k-dimensional base space B have positive curvature. These solutions depend on two extra parameters, other than the mass and the NUT charge. These are electric charge q and electric potential at infinity V. We investigate the existence of Taub-NUT solutions and find that in addition to the two conditions of uncharged NUT solutions, there exist two extra conditions. These two extra conditions come from the regularity of vector potential at r=N and the fact that the horizon at r=N should be the outer horizon of the NUT charged black hole. We find that the NUT solutions in 2k+2 dimensions have no curvature singularity at r=N, when the 2k-dimensional base space is chosen to be CP{sup 2k}. For bolt solutions, there exists an upper limit for the NUT parameter which decreases as the potential parameter increases. Second, we study the thermodynamics of these spacetimes. We compute temperature, entropy, charge, electric potential, action and mass of the black hole solutions, and find that these quantities satisfy the first law of thermodynamics. We perform a stability analysis by computing the heat capacity, and show that the NUT solutions are not thermally stable for even k's, while there exists a stable phase for odd k's, which becomes increasingly narrow with increasing dimensionality and wide with increasing V. We also study the phase behavior of the 4 and 6 dimensional bolt solutions in canonical ensemble and find that these solutions have a stable phase, which becomes smaller as V increases.
NASA Astrophysics Data System (ADS)
Kocsis, Bence; Loeb, Abraham
2014-09-01
Black holes are the ultimate prisons of the Universe, regions of spacetime where the enormous gravity prohibits matter or even light to escape to infinity. Yet, matter falling toward the black holes may shine spectacularly, generating the strongest source of radiation. These sources provide us with astrophysical laboratories of extreme physical conditions that cannot be realized on Earth. This chapter offers a review of the basic menus for feeding matter onto black holes and discusses their observational implications.
Noncommutative solitonic black hole
NASA Astrophysics Data System (ADS)
Chang-Young, Ee; Kimm, Kyoungtae; Lee, Daeho; Lee, Youngone
2012-05-01
We investigate solitonic black hole solutions in three-dimensional noncommutative spacetime. We do this in gravity with a negative cosmological constant coupled to a scalar field. Noncommutativity is realized with the Moyal product which is expanded up to first order in the noncommutativity parameter in two spatial directions. With numerical simulation we study the effect of noncommutativity by increasing the value of the noncommutativity parameter starting from commutative solutions. We find that even a regular soliton solution in the commutative case becomes a black hole solution when the noncommutativity parameter reaches a certain value.
NASA Astrophysics Data System (ADS)
Mišković, Olivera; Olea, Rodrigo
2011-01-01
Motivated by possible applications within the framework of anti-de Sitter gravity/conformal field theory correspondence, charged black holes with AdS asymptotics, which are solutions to Einstein-Gauss-Bonnet gravity in D dimensions, and whose electric field is described by nonlinear electrodynamics are studied. For a topological static black hole ansatz, the field equations are exactly solved in terms of the electromagnetic stress tensor for an arbitrary nonlinear electrodynamic Lagrangian in any dimension D and for arbitrary positive values of Gauss-Bonnet coupling. In particular, this procedure reproduces the black hole metric in Born-Infeld and conformally invariant electrodynamics previously found in the literature. Altogether, it extends to D>4 the four-dimensional solution obtained by Soleng in logarithmic electrodynamics, which comes from vacuum polarization effects. Falloff conditions for the electromagnetic field that ensure the finiteness of the electric charge are also discussed. The black hole mass and vacuum energy as conserved quantities associated to an asymptotic timelike Killing vector are computed using a background-independent regularization of the gravitational action based on the addition of counterterms which are a given polynomial in the intrinsic and extrinsic curvatures.
Miskovic, Olivera; Olea, Rodrigo
2011-01-15
Motivated by possible applications within the framework of anti-de Sitter gravity/conformal field theory correspondence, charged black holes with AdS asymptotics, which are solutions to Einstein-Gauss-Bonnet gravity in D dimensions, and whose electric field is described by nonlinear electrodynamics are studied. For a topological static black hole ansatz, the field equations are exactly solved in terms of the electromagnetic stress tensor for an arbitrary nonlinear electrodynamic Lagrangian in any dimension D and for arbitrary positive values of Gauss-Bonnet coupling. In particular, this procedure reproduces the black hole metric in Born-Infeld and conformally invariant electrodynamics previously found in the literature. Altogether, it extends to D>4 the four-dimensional solution obtained by Soleng in logarithmic electrodynamics, which comes from vacuum polarization effects. Falloff conditions for the electromagnetic field that ensure the finiteness of the electric charge are also discussed. The black hole mass and vacuum energy as conserved quantities associated to an asymptotic timelike Killing vector are computed using a background-independent regularization of the gravitational action based on the addition of counterterms which are a given polynomial in the intrinsic and extrinsic curvatures.
NASA Astrophysics Data System (ADS)
Li, Ran; Zhao, Jun-Kun
2016-04-01
We investigate the massive vector particles' Hawking radiation from the neutral rotating Anti-de Sitter (AdS) black holes in conformal gravity by using the tunneling method. It is well known that the dynamics of massive vector particles are governed by the Proca field equation. Applying WKB approximation to the Proca equation, the tunneling probabilities and radiation spectrums of the emitted particles are derived. Hawking temperature of the neutral rotating AdS black holes in conformal gravity is recovered, which is consistent with the previous result in the literature. Supported by the National Natural Science Foundation of China under Grant No. 11205048, and the Foundation for Young Key Teacher of Henan Normal University
Inner structure of black holes in Eddington-inspired Born-Infeld gravity: The role of mass inflation
NASA Astrophysics Data System (ADS)
Avelino, P. P.
2016-02-01
We investigate the interior dynamics of accreting black holes in Eddington-inspired Born-Infeld gravity using the homogeneous approximation and taking charge as a surrogate for angular momentum, showing that accretion can have an enormous impact on their inner structure. We find that, unlike in general relativity, there is a minimum accretion rate below which the mass inflation instability, which drives the center-of-mass streaming density to exponentially high values in an extremely short interval of time, does not occur. We further show that, above this threshold, mass inflation takes place inside black holes much in the same way as in general relativity, but is brought to a halt at an energy density which is, in general, much smaller than the fundamental energy density of the theory. We conjecture that some of these results may be a common feature of modified gravity theories in which significant deviations from general relativity manifest themselves at high densities.
Uniqueness theorem for black holes with Kaluza-Klein asymptotic in 5D Einstein-Maxwell gravity
Yazadjiev, Stoytcho
2010-07-15
In the present paper, we prove a uniqueness theorem for stationary multi-black hole configurations with Kaluza-Klein asymptotic in a certain sector of 5D Einstein-Maxwell gravity. As a part of the technical assumptions in the theorem, we assume that the Killing vector associated with the compact dimension is orthogonal to the other Killing vectors and that it is also hypersurface orthogonal. About the Maxwell field, we assume that it is invariant under the Killing symmetries and has a nonzero component only along the Killing vector associated with the compact dimension. We show that such multi-black hole configurations are uniquely specified by the interval structure, angular momenta of the horizons, magnetic charges, and the magnetic flux. A straightforward generalization of the uniqueness theorem for 5D Einstein-Maxwell-dilaton gravity is also given.
Spherically symmetric black holes in f (R) gravity: is geometric scalar hair supported?
NASA Astrophysics Data System (ADS)
Cañate, Pedro; Jaime, Luisa G.; Salgado, Marcelo
2016-08-01
We critically discuss current research on black hole (BH) solutions in f (R) gravity and shed light on its geometrical and physical significance. We also investigate the meaning, existence or lack thereof of Birkhoff’s theorem (BT) in this kind of modified gravity. We then focus on the analysis and search for non-trivial (i.e. hairy) asymptotically flat (AF) BH solutions in static and spherically symmetric (SSS) spacetimes in vacuum having the property that the Ricci scalar does not vanish identically in the domain of outer communication. To do so, we provide and enforce regularity conditions at the horizon in order to prevent the presence of singular solutions there. Specifically, we consider several classes of f (R) models like those proposed recently for explaining the accelerated expansion in the Universe and which have been thoroughly tested in several physical scenarios. Finally, we report analytical and numerical evidence about the absence of geometric hair in AFSSSBH solutions in those f (R) models. First, we submit the models to the available no-hair theorems (NHTs), and in the cases where the theorems apply, the absence of hair is demonstrated analytically. In the cases where the theorems do not apply, we resort to a numerical analysis due to the complexity of the non-linear differential equations. With that aim, a code to solve the equations numerically was built and tested using well-known exact solutions. In a future investigation we plan to analyze the problem of hair in de Sitter and anti-de Sitter backgrounds.
Black hole solutions in de Rham-Gabadadze-Tolley massive gravity
NASA Astrophysics Data System (ADS)
Li, Ping; Li, Xin-zhou; Xi, Ping
2016-03-01
We present a detailed study of the static spherically symmetric solutions in de Rham-Gabadadze-Tolley (dRGT) theory. Since the diffeomorphism invariance can be restored by introducing the Stückelberg fields ϕa , there is new invariant Ia b=gμ ν∂μϕa∂νϕb in the massive gravity, which adds to the ones usually encountered in general relativity (GR). In the unitary gauge ϕa=xμδμa, any inverse metric gμ ν that has divergence including the coordinate singularity in GR would exhibit a singularity in the invariant Ia b. Therefore, there is no conventional Schwarzschild metric if we choose unitary gauge. In this paper, we obtain a self-consistent static spherically symmetric ansatz in the nonunitary gauge. Under this ansatz, we find that there are seven solutions including the Schwarzschild solution, Reissner-Nordström solution and five other solutions. These solutions may possess an event horizon depending upon the physical parameters (Schwarzschild radius rs, scalar charge S and/or electric charge Q ). If these solutions possess an event horizon, we show that the singularity of Ia b is absent at the horizon. Therefore, these solutions may become candidates for black holes in dRGT.
Quantum corrections to Bekenstein-Hawking black hole entropy and gravity partition functions
NASA Astrophysics Data System (ADS)
Bytsenko, A. A.; Tureanu, A.
2013-08-01
Algebraic aspects of the computation of partition functions for quantum gravity and black holes in AdS3 are discussed. We compute the sub-leading quantum corrections to the Bekenstein-Hawking entropy. It is shown that the quantum corrections to the classical result can be included systematically by making use of the comparison with conformal field theory partition functions, via the AdS3/CFT2 correspondence. This leads to a better understanding of the role of modular and spectral functions, from the point of view of the representation theory of infinite-dimensional Lie algebras. Besides, the sum of known quantum contributions to the partition function can be presented in a closed form, involving the Patterson-Selberg spectral function. These contributions can be reproduced in a holomorphically factorized theory whose partition functions are associated with the formal characters of the Virasoro modules. We propose a spectral function formulation for quantum corrections to the elliptic genus from supergravity states.
NASA Astrophysics Data System (ADS)
Yang, Huan; Zimmerman, Aaron; Lehner, Luis
2015-02-01
We demonstrate that rapidly spinning black holes can display a new type of nonlinear parametric instability—which is triggered above a certain perturbation amplitude threshold—akin to the onset of turbulence, with possibly observable consequences. This instability transfers from higher temporal and azimuthal spatial frequencies to lower frequencies—a phenomenon reminiscent of the inverse cascade displayed by (2 +1 )-dimensional fluids. Our finding provides evidence for the onset of transitory turbulence in astrophysical black holes and predicts observable signatures in black hole binaries with high spins. Furthermore, it gives a gravitational description of this behavior which, through the fluid-gravity duality, can potentially shed new light on the remarkable phenomena of turbulence in fluids.
NASA Technical Reports Server (NTRS)
Centrella, Joan
2012-01-01
The final merger of two black holes is expected to be the strongest source of gravitational waves for both ground-based detectors such as LIGO and VIRGO, as well as future. space-based detectors. Since the merger takes place in the regime of strong dynamical gravity, computing the resulting gravitational waveforms requires solving the full Einstein equations of general relativity on a computer. For many years, numerical codes designed to simulate black hole mergers were plagued by a host of instabilities. However, recent breakthroughs have conquered these instabilities and opened up this field dramatically. This talk will focus on.the resulting 'gold rush' of new results that is revealing the dynamics and waveforms of binary black hole mergers, and their applications in gravitational wave detection, testing general relativity, and astrophysics
NASA Technical Reports Server (NTRS)
Centrella, Joan
2010-01-01
The final merger of two black holes is expected to be the strongest source of gravitational waves for both ground-based detectors such as LIGO and VIRGO, as well as the space-based LISA. Since the merger takes place in the regime of strong dynamical gravity, computing the resulting gravitational waveforms requires solving the full Einstein equations of general relativity on a computer. For many years, numerical codes designed to simulate black hole mergers were plagued by a host of instabilities. However, recent breakthroughs have conquered these instabilities and opened up this field dramatically. This talk will focus on the resulting gold rush of new results that are revealing the dynamics and waveforms of binary black hole mergers, and their applications in gravitational wove detection, testing general relativity, and astrophysics.
Yang, Huan; Zimmerman, Aaron; Lehner, Luis
2015-02-27
We demonstrate that rapidly spinning black holes can display a new type of nonlinear parametric instability-which is triggered above a certain perturbation amplitude threshold-akin to the onset of turbulence, with possibly observable consequences. This instability transfers from higher temporal and azimuthal spatial frequencies to lower frequencies-a phenomenon reminiscent of the inverse cascade displayed by (2+1)-dimensional fluids. Our finding provides evidence for the onset of transitory turbulence in astrophysical black holes and predicts observable signatures in black hole binaries with high spins. Furthermore, it gives a gravitational description of this behavior which, through the fluid-gravity duality, can potentially shed new light on the remarkable phenomena of turbulence in fluids. PMID:25768746
BLACK HOLE AURORA POWERED BY A ROTATING BLACK HOLE
Takahashi, Masaaki; Takahashi, Rohta
2010-05-15
We present a model for high-energy emission sources generated by a standing magnetohydrodynamical (MHD) shock in a black hole magnetosphere. The black hole magnetosphere would be constructed around a black hole with an accretion disk, where a global magnetic field could be originated by currents in the accretion disk and its corona. Such a black hole magnetosphere may be considered as a model for the central engine of active galactic nuclei, some compact X-ray sources, and gamma-ray bursts. The energy sources of the emission from the magnetosphere are the gravitational and electromagnetic energies of magnetized accreting matters and the rotational energy of a rotating black hole. When the MHD shock generates in MHD accretion flows onto the black hole, the plasma's kinetic energy and the black hole's rotational energy can convert to radiative energy. In this Letter, we demonstrate the huge energy output at the shock front by showing negative energy postshock accreting MHD flows for a rapidly rotating black hole. This means that the extracted energy from the black hole can convert to the radiative energy at the MHD shock front. When an axisymmetric shock front is formed, we expect a ring-shaped region with very hot plasma near the black hole; this would look like an 'aurora'. The high-energy radiation generated from there would carry to us the information for the curved spacetime due to the strong gravity.
Thermodynamics of Lifshitz black holes
NASA Astrophysics Data System (ADS)
Devecioǧlu, Deniz Olgu; Sarıoǧlu, Özgür
2011-06-01
We apply the recently extended conserved Killing charge definition of Abbott-Deser-Tekin formalism to compute, for the first time, the energies of analytic Lifshitz black holes in higher dimensions. We then calculate the temperature and the entropy of this large family of solutions, and study and discuss the first law of black hole thermodynamics. Along the way we also identify the possible critical points of the relevant quadratic curvature gravity theories. Separately, we also apply the generalized Killing charge definition to compute the energy and the angular momentum of the warped AdS3 black hole solution of the three-dimensional new massive gravity theory.
NASA Astrophysics Data System (ADS)
Centrella, Joan
2009-05-01
The final merger of two black holes is expected to be the strongest gravitational wave source for ground-based interferometers such as LIGO, VIRGO, and GEO600, as well as the space-based LISA. Observing these sources with gravitational wave detectors requires that we know the radiation waveforms they emit. And, when the black holes merge in the presence of gas and magnetic fields, various types of electromagnetic signals may also be produced. Since these mergers take place in regions of extreme gravity, we need to solve Einstein's equations of general relativity on a computer. For more than 30 years, scientists have tried to compute black hole mergers using the methods of numerical relativity. The resulting computer codes have been plagued by instabilities, causing them to crash well before the black holes in the binary could complete even a single orbit. Within the past few years, however, this situation has changed dramatically, with a series of remarkable breakthroughs. This talk will focus on new simulations that are revealing the dynamics and waveforms of binary black hole mergers, and their applications in gravitational wave detection, testing general relativity, and astrophysics.
NASA Technical Reports Server (NTRS)
Centrella, John
2009-01-01
The final merger of two black holes is expected to be the strongest gravitational wave source for ground-based interferometers such as LIGO, VIRGO, and GEO600, as well as the space-based LISA. Observing these sources with gravitational wave detectors requires that we know the radiation waveforms they emit. And, when the black holes merge in the presence of gas and magnetic fields, various types of electromagnetic signals may also be produced. Since these mergers take place in regions of extreme gravity, we need to solve Einstein's equations of general relativity on a computer. For more than 30 years, scientists have tried to compute black hole mergers using the methods of numerical relativity. The resulting computer codes have been plagued by instabilities, causing them to crash well before the black holes in the binary could complete even a single orbit. Within the past few years, however, this situation has changed dramatically, with a series of remarkable breakthroughs. This talk will focus on new simulations that are revealing the dynamics and waveforms of binary black hole mergers, and their applications in gravitational wave detection, testing general relativity, and astrophysics.
Extremal dyonic black holes in D=4 Gauss-Bonnet gravity
Chen, C.-M.; Gal'tsov, Dmitri V.; Orlov, Dmitry G.
2008-11-15
We investigate extremal dyon black holes in the Einstein-Maxwell-dilaton theory with higher curvature corrections in the form of the Gauss-Bonnet density coupled to the dilaton. In the same theory without the Gauss-Bonnet term the extremal dyon solutions exist only for discrete values of the dilaton coupling constant a. We show that the Gauss-Bonnet term acts as a dyon hair tonic enlarging the allowed values of a to continuous domains in the plane (a,q{sub m}) where q{sub m} is the magnetic charge. In the limit of the vanishing curvature coupling (a large magnetic charge) the dyon solutions obtained tend to the Reissner-Nordstroem solution but not to the extremal dyons of the Einstein-Maxwell-dilaton theory. Both solutions have the same dependence of the horizon radius in terms of charges. The entropy of new dyonic black holes interpolates between the Bekenstein-Hawking value in the limit of the large magnetic charge (equivalent to the vanishing Gauss-Bonnet coupling) and twice this value for the vanishing magnetic charge. Although an expression for the entropy can be obtained analytically using purely local near-horizon solutions, its interpretation as the black hole entropy is legitimate only once the global black hole solution is known to exist, and we obtain numerically the corresponding conditions on the parameters. Thus, a purely local analysis is insufficient to fully understand the entropy of the curvature-corrected black holes. We also find dyon solutions which are not asymptotically flat, but approach the linear dilaton background at infinity. They describe magnetic black holes on the electric linear dilaton background.
Extremal dyonic black holes in D=4 Gauss-Bonnet gravity
NASA Astrophysics Data System (ADS)
Chen, Chiang-Mei; Gal'Tsov, Dmitri V.; Orlov, Dmitry G.
2008-11-01
We investigate extremal dyon black holes in the Einstein-Maxwell-dilaton theory with higher curvature corrections in the form of the Gauss-Bonnet density coupled to the dilaton. In the same theory without the Gauss-Bonnet term the extremal dyon solutions exist only for discrete values of the dilaton coupling constant a. We show that the Gauss-Bonnet term acts as a dyon hair tonic enlarging the allowed values of a to continuous domains in the plane (a,qm) where qm is the magnetic charge. In the limit of the vanishing curvature coupling (a large magnetic charge) the dyon solutions obtained tend to the Reissner-Nordström solution but not to the extremal dyons of the Einstein-Maxwell-dilaton theory. Both solutions have the same dependence of the horizon radius in terms of charges. The entropy of new dyonic black holes interpolates between the Bekenstein-Hawking value in the limit of the large magnetic charge (equivalent to the vanishing Gauss-Bonnet coupling) and twice this value for the vanishing magnetic charge. Although an expression for the entropy can be obtained analytically using purely local near-horizon solutions, its interpretation as the black hole entropy is legitimate only once the global black hole solution is known to exist, and we obtain numerically the corresponding conditions on the parameters. Thus, a purely local analysis is insufficient to fully understand the entropy of the curvature-corrected black holes. We also find dyon solutions which are not asymptotically flat, but approach the linear dilaton background at infinity. They describe magnetic black holes on the electric linear dilaton background.
Black hole hair in generalized scalar-tensor gravity: An explicit example
NASA Astrophysics Data System (ADS)
Sotiriou, Thomas P.; Zhou, Shuang-Yong
2014-12-01
In a recent paper we showed that in shift-symmetric Horndeski theory the scalar field is forced to obtain a nontrivial configuration in black hole spacetimes, unless a linear coupling with the Gauss-Bonnet invariant is tuned away. As a result, black holes generically have hair in this theory. In this companion paper, we first review our argument and discuss it in more detail. We then present actual black hole solutions in the simplest case of a theory with the linear scalar-Gauss-Bonnet coupling. We generate exact solutions numerically for a wide range of values of the coupling and also construct analytic solutions perturbatively in the small-coupling limit. Comparison of the two types of solutions indicates that nonlinear effects that are not captured by the perturbative solution lead to a finite area, as opposed to a central, singularity. Remarkably, black holes have a minimum size, controlled by the length scale associated with the scalar-Gauss-Bonnet coupling. We also compute some phenomenological observables for the numerical solution for a wide range of values of the scalar-Gauss-Bonnet coupling. Deviations from the Schwarzschild geometry are generically very small.
NASA Technical Reports Server (NTRS)
2006-01-01
[figure removed for brevity, see original site] Poster Version
This artist's concept shows a supermassive black hole at the center of a remote galaxy digesting the remnants of a star. NASA's Galaxy Evolution Explorer had a 'ringside' seat for this feeding frenzy, using its ultraviolet eyes to study the process from beginning to end.
The artist's concept chronicles the star being ripped apart and swallowed by the cosmic beast over time. First, the intact sun-like star (left) ventures too close to the black hole, and its own self-gravity is overwhelmed by the black hole's gravity. The star then stretches apart (middle yellow blob) and eventually breaks into stellar crumbs, some of which swirl into the black hole (cloudy ring at right). This doomed material heats up and radiates light, including ultraviolet light, before disappearing forever into the black hole. The Galaxy Evolution Explorer was able to watch this process unfold by observing changes in ultraviolet light.
The area around the black hole appears warped because the gravity of the black hole acts like a lens, twisting and distorting light.
NASA Astrophysics Data System (ADS)
Cordes, J. M.; Kramer, M.; Backer, D. C.; Lazio, T. J. W.; Science Working Groupthe Square Kilometer Array Team
2005-12-01
A Galactic census of pulsars with the SKA will discover most of the active pulsars in the Galaxy beamed toward us. The sheer number of pulsars discovered, along with the exceptional timing precision the SKA can provide, will revolutionize the field of pulsar astrophysics and will enable significant tests of theories of gravity. Census discoveries will almost certainly include pulsar-black hole binaries as well as pulsars orbiting the super-massive black hole in the Galactic center. These systems provide unique opportunties for probing the ultra-strong field limit of relativistic gravity and will complement future gravitational wave detections using LISA-like instruments. SKA measurements can be used to test the Cosmic Censorship Conjecture and the No-Hair theorem. The large number of millisecond pulsars discovered with the SKA will also provide a dense array of precision clocks on the sky that can be used as multiple arms of a cosmic gravitational wave detector, which can be used to detect and measure the stochastic cosmological gravitational wave background that is expected from a number of sources. In addition to gravitational tests, the large number of lines of sight will provide a detailed map of the Galaxy's electron density and magnetic fields and important information on the dynamics and evolutionary histories of neutron stars. The census will provide examples of nearly every possible outcome of the evolution of massive stars, including (as above) pulsar black-hole systems and sub-millisecond pulsars, if they exist. These objects will yield constraints on the equation of state of matter at super-nuclear densities. Masses of pulsars and their binary companions planets, white dwarfs, other neutron stars, and black holes will be determined to ˜ 1% for hundreds of objects. The SKA will also provide partial censuses of nearby galaxies through periodicity and giant-pulse detections, yielding important information on the intergalactic medium.
NASA Technical Reports Server (NTRS)
Baker, John
2010-01-01
Among the fascinating phenomena predicted by General Relativity, Einstein's theory of gravity, black holes and gravitational waves, are particularly important in astronomy. Though once viewed as a mathematical oddity, black holes are now recognized as the central engines of many of astronomy's most energetic cataclysms. Gravitational waves, though weakly interacting with ordinary matter, may be observed with new gravitational wave telescopes, opening a new window to the universe. These observations promise a direct view of the strong gravitational dynamics involving dense, often dark objects, such as black holes. The most powerful of these events may be merger of two colliding black holes. Though dark, these mergers may briefly release more energy that all the stars in the visible universe, in gravitational waves. General relativity makes precise predictions for the gravitational-wave signatures of these events, predictions which we can now calculate with the aid of supercomputer simulations. These results provide a foundation for interpreting expect observations in the emerging field of gravitational wave astronomy.
Null geodesics and shadow of a rotating black hole in extended Chern-Simons modified gravity
Amarilla, Leonardo; Eiroa, Ernesto F.; Giribet, Gaston
2010-06-15
The Chern-Simons modification to general relativity in four dimensions consists of adding to the Einstein-Hilbert term a scalar field that couples to the first-class Pontryagin density. In this theory, which has attracted considerable attention recently, the Schwarzschild metric persists as an exact solution, and this is why this model resists several observational constraints. In contrast, the spinning black hole solution of the theory is not given by the Kerr metric but by a modification of it, so far only known for slow rotation and small coupling constant. In the present paper, we show that, in this approximation, the null geodesic equation can be integrated, and this allows us to investigate the shadow cast by a black hole. We discuss how, in addition to the angular momentum of the solution, the coupling to the Chern-Simons term deforms the shape of the shadow.
Black hole accretion disks in brane gravity via a confining potential
NASA Astrophysics Data System (ADS)
Heydari-Fard, Malihe
2010-12-01
Accretion disks are among the most luminous and ubiquitous sources in astrophysics and they have drawn a good deal of attention from the observational and theoretical communities. In this paper, we study the process of matter forming thin accretion disks around black hole solutions in the context of the brane-world scenario where our universe is a three-brane embedded in an m-dimensional bulk and localization of matter on the brane is achieved by means of a confining potential. The physical properties of thin accretion disks including the time averaged energy flux, temperature distribution, the emission spectrum as well as the energy conversion efficiency are obtained, and the results are compared with the DMPR, CFM and BMD brane black holes and the standard general relativistic Schwarzschild solution.
Combinatorics of the SU(2) black hole entropy in loop quantum gravity
Agullo, Ivan; Barbero G, J. Fernando; Borja, Enrique F.; Diaz-Polo, Jacobo; Villasenor, Eduardo J. S.
2009-10-15
We use the combinatorial and number-theoretical methods developed in previous works by the authors to study black hole entropy in the new proposal put forth by Engle, Noui, and Perez. Specifically, we give the generating functions relevant for the computation of the entropy and use them to derive its asymptotic behavior, including the value of the Immirzi parameter and the coefficient of the logarithmic correction.
Probability for a primordial black hole pair in 1/R gravity
Paul, Dilip; Paul, Bikash Chandra
2005-09-15
The probability for quantum creation of an inflationary universe with a pair of black holes in 1/R-gravitational theory has been studied. Considering a gravitational action which includes a cosmological constant ({lambda}) in addition to {delta}R{sup -1} term, the probability has been evaluated in a semiclassical approximation with Hartle-Hawking boundary condition. We obtain instanton solutions determined by the parameters {delta} and {lambda} satisfying the constraint {delta}{<=}(4{lambda}{sup 2}/3). However, we note that two different classes of instanton solutions exists in the region 0<{delta}<(4{lambda}{sup 2}/3). The probabilities of creation of such configurations are evaluated. It is found that the probability of creation of a universe with a pair of black holes is strongly suppressed with a positive cosmological constant except in one case when 0<{delta}<{lambda}{sup 2}. It is also found that gravitational instanton solution is permitted even with {lambda}=0 but one has to consider {delta}<0. However, in the later case a universe with a pair of black holes is less probable.
NASA Astrophysics Data System (ADS)
Fukue, Jun
2000-08-01
A black hole falling into the Earth would syndrome toward the center, while it would shine through mass accretion. The author has re-examined the dynamics of such a black hole in the Earth. In the case of a non-radiating black hole, the timescale of the syndrome is inversely proportional to the initial mass of the black hole. In the case of a radiating black hole, on the other hand, the syndrome time is of the order of the Eddington time. The radiating black hole in the Earth would act as a strong heat source.
Thermodynamics of topological black holes in Brans-Dicke gravity with a power-law Maxwell field
NASA Astrophysics Data System (ADS)
Zangeneh, M. Kord; Dehghani, M. H.; Sheykhi, A.
2015-11-01
In this paper, we present a new class of higher-dimensional exact topological black hole solutions of the Brans-Dicke theory in the presence of a power-law Maxwell field as the matter source. For this aim, we introduce a conformal transformation which transforms the Einstein-dilaton-power-law Maxwell gravity Lagrangian to the Brans-Dicke-power-law Maxwell theory one. Then, by using this conformal transformation, we obtain the desired solutions. Next, we study the properties of the solutions and conditions under which we have black holes. Interestingly enough, we show that there is a cosmological horizon in the presence of a negative cosmological constant. Finally, we calculate the temperature and charge and then by calculating the Euclidean action, we obtain the mass, the entropy and the electromagnetic potential energy. We find that the entropy does not respect the area law, and also the conserved and thermodynamic quantities are invariant under conformal transformation. Using these thermodynamic and conserved quantities, we show that the first law of black hole thermodynamics is satisfied on the horizon.
Giribet, Gaston; Oliva, Julio; Tempo, David; Troncoso, Ricardo
2009-12-15
Asymptotically anti-de Sitter rotating black holes for the Bergshoeff-Hohm-Townsend massive gravity theory in three dimensions are considered. In the special case when the theory admits a unique maximally symmetric solution, apart from the mass and the angular momentum, the black hole is described by an independent 'gravitational hair' parameter, which provides a negative lower bound for the mass. This bound is saturated at the extremal case, and since the temperature and the semiclassical entropy vanish, it is naturally regarded as the ground state. The absence of a global charge associated with the gravitational hair parameter reflects itself through the first law of thermodynamics in the fact that the variation of this parameter can be consistently reabsorbed by a shift of the global charges, giving further support to consider the extremal case as the ground state. The rotating black hole fits within relaxed asymptotic conditions as compared with the ones of Brown and Henneaux, such that they are invariant under the standard asymptotic symmetries spanned by two copies of the Virasoro generators, and the algebra of the conserved charges acquires a central extension. Then it is shown that Strominger's holographic computation for general relativity can also be extended to the Bergshoeff-Hohm-Townsend theory; i.e., assuming that the quantum theory could be consistently described by a dual conformal field theory at the boundary, the black hole entropy can be microscopically computed from the asymptotic growth of the number of states according to Cardy's formula, in exact agreement with the semiclassical result.
NASA Astrophysics Data System (ADS)
Hendi, S. H.; Panahiyan, S.; Momennia, M.
2016-04-01
In this paper, we consider quadratic Maxwell invariant as a correction to the Maxwell theory and study thermodynamic behavior of the black holes in Einstein and Gauss-Bonnet gravities. We consider cosmological constant as a thermodynamic pressure to extend phase space. Next, we obtain critical values in case of variation of nonlinearity and Gauss-Bonnet parameters. Although the general thermodynamical behavior of the black hole solutions is the same as usual Van der Waals system, we show that in special case of the nonlinear electromagnetic field, there will be a turning point for the phase diagrams and usual Van der Waals is not observed. This theory of nonlinear electromagnetic field provides two critical horizon radii. We show that this unusual behavior of phase diagrams is due to existence of second critical horizon radius. It will be pointed out that the power of the gravity and nonlinearity of the matter field modify the critical values. We generalize the study by considering the effects of dimensionality on critical values and make comparisons between our models with their special sub-classes. In addition, we examine the possibility of the existence of the reentrant phase transitions through two different methods.
In this NASA Now episode, Dr. Daniel Patnaude talks about how his team discovered a baby black hole, why this is important and how black holes create tidal forces. Throughout his discussion, Patnau...
NASA Astrophysics Data System (ADS)
Prasia, P.; Kuriakose, V. C.
2016-07-01
We investigate black holes in a class of dRGT massive gravity for their quasi normal modes (QNMs) for neutral and charged ones using Improved Asymptotic Iteration Method and their thermodynamic behavior. The QNMs are studied for different values of the massive parameter m_g for both neutral and charged dRGT black holes under a massless scalar perturbation. As m_g increases, the magnitude of the quasi normal frequencies are found to be increasing. The results are also compared with the Schwarzchild de Sitter case. P-V criticallity of the aforesaid black hoels under massles scalar perturbation in the de Sitter space are also studied in this paper. It is found that the thermodynamic behavior of a neutral black hole shows no physically feasible phase transition while a charged black hole shows a definite phase transition.
NASA Technical Reports Server (NTRS)
Dolan, Joseph F.; Fisher, Richard R. (Technical Monitor)
2001-01-01
When asked to discuss Cyg XR-1, E. E. Salpeter once concluded, 'A black hole in Cyg X(R)-1 is the most conservative hypothesis.' Recent observations now make it likely that a black hole in Cyg XR-1 is the only hypothesis tenable. Chandrasekhar first showed that compact stars - those with the inward force of gravity on their outer layers balanced by the pressure generated by the Pauli exclusion principle acting on its electrons (in white dwarfs) or nucleons (in neutron stars) - have a maximum mass. Equilibrium is achieved at a minimum of the total energy of the star, which is the sum of the positive Fermi energy and the negative gravitational energy. The maximum mass attainable in equilibrium is found by setting E = 0: M(max) = 1.5 M(Sun). If the mass of the star is larger than this, then E can be decreased without bound by decreasing the star's radius and increasing its (negative) gravitational energy. No equilibrium value of the radius exist, and general relativity predicts that gravitational collapse to a point occurs. This point singularity is a black hole.
Quantum compositeness of gravity: black holes, AdS and inflation
Dvali, Gia; Gomez, Cesar
2014-01-14
Gravitational backgrounds, such as black holes, AdS, de Sitter and inflationary universes, should be viewed as composite of N soft constituent gravitons. It then follows that such systems are close to quantum criticality of graviton Bose-gas to Bose-liquid transition. Generic properties of the ordinary metric description, including geodesic motion or particle-creation in the background metric, emerge as the large-N limit of quantum scattering of constituent longitudinal gravitons. We show that this picture correctly accounts for physics of large and small black holes in AdS, as well as reproduces well-known inflationary predictions for cosmological parameters. However, it anticipates new effects not captured by the standard semi-classical treatment. In particular, we predict observable corrections that are sensitive to the inflationary history way beyond last 60 e-foldings. We derive an absolute upper bound on the number of e-foldings, beyond which neither de Sitter nor inflationary Universe can be approximated by a semi-classical metric. However, they could in principle persist in a new type of quantum eternity state. We discuss implications of this phenomenon for the cosmological constant problem.
Quantum compositeness of gravity: black holes, AdS and inflation
Dvali, Gia; Gomez, Cesar E-mail: cesar.gomez@uam.es
2014-01-01
Gravitational backgrounds, such as black holes, AdS, de Sitter and inflationary universes, should be viewed as composite of N soft constituent gravitons. It then follows that such systems are close to quantum criticality of graviton Bose-gas to Bose-liquid transition. Generic properties of the ordinary metric description, including geodesic motion or particle-creation in the background metric, emerge as the large-N limit of quantum scattering of constituent longitudinal gravitons. We show that this picture correctly accounts for physics of large and small black holes in AdS, as well as reproduces well-known inflationary predictions for cosmological parameters. However, it anticipates new effects not captured by the standard semi-classical treatment. In particular, we predict observable corrections that are sensitive to the inflationary history way beyond last 60 e-foldings. We derive an absolute upper bound on the number of e-foldings, beyond which neither de Sitter nor inflationary Universe can be approximated by a semi-classical metric. However, they could in principle persist in a new type of quantum eternity state. We discuss implications of this phenomenon for the cosmological constant problem.
NASA Astrophysics Data System (ADS)
Levin, Janna; D'Orazio, Daniel
2016-03-01
Black holes are dark dead stars. Neutron stars are giant magnets. As the neutron star orbits the black hole, an electronic circuit forms that generates a blast of power just before the black hole absorbs the neutron star whole. The black hole battery conceivably would be observable at cosmological distances. Possible channels for luminosity include synchro-curvature radiation, a blazing fireball, or even an unstable, short-lived black hole pulsar. As suggested by Mingarelli, Levin, and Lazio, some fraction of the battery power could also be reprocessed into coherent radio emission to populate a subclass of fast radio bursts.
More Hidden Black Hole Dangers
NASA Technical Reports Server (NTRS)
Wanjek, Christopher
2003-01-01
Black holes such as GRO J1655-40 form from collapsed stars. When stars at least eight times more massive than our Sun exhaust their fuel supply, they no longer have the energy to support their tremendous bulk. These stars explode as supernovae, blasting their outer envelopes into space. If the core is more than three times the mass of the Sun, it will collapse into a singularity, a single point of infinite density.Although light cannot escape black holes, astronomers can see black holes by virtue of the hot, glowing gas often stolen from a neighboring star that orbits these objects. From our vantage point, the light seems to flicker. The Rossi Explorer has recorded this flickering (called quasiperiodic oscillations, or QPOs) around many black holes. QPOs are produced by gas very near the innermost stable orbit the closest orbit a blob of gas can maintain before falling pell-mell into the black hole. As gas whips around the black hole at near light speed, gravity pulls the gas in one direction, then another, adding to the flickering. The QPO is related to the speed and size of this orbit and the mass of the black hole.
A nonsingular rotating black hole
NASA Astrophysics Data System (ADS)
Ghosh, Sushant G.
2015-11-01
The spacetime singularities in classical general relativity are inevitable, as predicated by the celebrated singularity theorems. However, it is a general belief that singularities do not exist in Nature and that they are the limitations of the general relativity. In the absence of a well-defined quantum gravity, models of regular black holes have been studied. We employ a probability distribution inspired mass function m( r) to replace the Kerr black hole mass M to represent a nonsingular rotating black hole that is identified asymptotically (r ≫ k, k>0 constant) exactly as the Kerr-Newman black hole, and as the Kerr black hole when k=0. The radiating counterpart renders a nonsingular generalization of Carmeli's spacetime as well as Vaidya's spacetime, in the appropriate limits. The exponential correction factor changing the geometry of the classical black hole to remove the curvature singularity can also be motivated by quantum arguments. The regular rotating spacetime can also be understood as a black hole of general relativity coupled to nonlinear electrodynamics.
Prisons of Light - Black Holes
NASA Astrophysics Data System (ADS)
Ferguson, Kitty
1998-02-01
Prologue; 1. A cosmic case of burnout; 2. Matters of gravity: Newton and Einstein; 3. The capture of light; 4. Tripping the theoretical fantastic; 5. Crossing the bar; 6. Contemplating an enormous nothing; 7. Evidence in the case; 8. Hearts of darkness; 9. The search goes on; 10. Passages into the labyrinth; 11. Black hole legends and far out ideas; Epilogue.
Stability of the Schwarzschild-de Sitter black hole in the dRGT massive gravity theory
NASA Astrophysics Data System (ADS)
Kodama, Hideo; Arraut, Ivan
2014-03-01
The Schwarzschild-de Sitter solution in the Einstein theory with a positive cosmological constant Λ =m^2/α becomes an exact solution to the de Rham-Gabadadze-Tolley (dRGT) nonlinear massive gravity theory with the mass parameter m when the theory parameters α and β satisfy the relation β =α ^2. We study the perturbative behavior of this black hole solution in the nonlinear dRGT theory with β =α ^2. We find that the linear perturbation equations become identical to those for the vacuum Einstein theory when they are expressed in terms of gauge-invariant variables. This implies that this black hole is stable in the dRGT theory as far as the spacetime structure is concerned, in contrast to the case of the bi-Schwarzschild solution in the bi-metric theory. However, we have also found a pathological feature that the general solution to the perturbation equations contain a single arbitrary function of spacetime coordinates. This implies a degeneracy of dynamics in the Stückelberg field sector at the linear perturbation level in this background. The physical significance of this degeneracy depends on how the Stückelberg fields couple observable fields.
NASA Astrophysics Data System (ADS)
Borzou, Ahmad; Lin, Kai; Wang, Anzhong
2012-02-01
In this paper, we study electromeganetic static spacetimes in the nonrelativisitc general covariant theory of the Hořava-Lifshitz (HL) gravity, proposed recently by Hořava and Melby-Thompson, and present all the electric static solutions, which represent the generalization of the Reissner-Nordström solution found in Einstein's general relativity (GR). The global/local structures of spacetimes in the HL theory in general are different from those given in GR, because the dispersion relations of test particles now contain high-order momentum terms, so the speeds of these particles are unbounded in the ultraviolet (UV). As a result, the conception of light-cones defined in GR becomes invalid and test particles do not follow geodesics. To study black holes in the HL theory, we adopt the geometrical optical approximations, and define a horizon as a (two-closed) surface that is free of spacetime singularities and on which massless test particles are infinitely redshifted. With such a definition, we show that some of our solutions give rise to (charged) black holes, although the radii of their horizons in general depend on the energies of the test particles.
NASA Astrophysics Data System (ADS)
Mehdipour, S. Hamid
2013-06-01
We study some features of entropic force approach in the presence of a noncommutative Schwarzschild-deSitter black hole. In this setup, there exists a similarity between the small and large scales. There are two finite cut-off in very short and long distances wherein the force and energy graph stop abruptly at those scales. We find that the existence of a deSitter core around the origin, induced by noncommutativity, in addition to a standard deSitter background at large scale may lead to a violation of the equivalence principle. Finally in order to directly observe the finite cut-off at short-scale gravity, caused by noncommutativity quantum fluctuations, we derive an effective gravitational constant.
NASA Astrophysics Data System (ADS)
Xie, Zhi-Kun; Pan, Wei-Zhen; Yang, Xue-Jun
2013-03-01
Using a new tortoise coordinate transformation, we discuss the quantum nonthermal radiation characteristics near an event horizon by studying the Hamilton-Jacobi equation of a scalar particle in curved space-time, and obtain the event horizon surface gravity and the Hawking temperature on that event horizon. The results show that there is a crossing of particle energy near the event horizon. We derive the maximum overlap of the positive and negative energy levels. It is also found that the Hawking temperature of a black hole depends not only on the time, but also on the angle. There is a problem of dimension in the usual tortoise coordinate, so the present results obtained by using a correct-dimension new tortoise coordinate transformation may be more reasonable.
NASA Astrophysics Data System (ADS)
Sciama, D. W.
A physical account of the processes of black hole explosions is presented. Black holes form when the degeneracy pressure in a neutron star can no longer balance gravitational forces because the mass of the star is too large. Although black holes absorb surrounding matter through the action of a gravitational field, quantum fluctuations have been theoretically demonstrated to occur in the vacuum, and feature a thermal character. The temperature field decreases outwards, in accordance with the nonuniformity of the gravitational field, but does allow thermal radiation, i.e., Hawking radiation, to escape the black hole. The time scale for the radiation shortens as the mass of the black hole decreases, until a time scale is reached which is short enough for the process to be called an explosion. Observations of electron-positron Hawking radiation are suggested to offer proof of a black hole explosion.
NASA Astrophysics Data System (ADS)
Chung, Hyeyoun
2015-10-01
This thesis explores the evolution of different types of black holes, and the ways in which black hole dynamics can be used to answer questions about other physical systems. We first investigate the differences in observable gravitational effects between a four-dimensional Randall-Sundrum (RS) braneworld universe compared to a universe without the extra dimension, by considering a black hole solution to the braneworld model that is localized on the brane. When the brane has a negative cosmological constant, then for a certain range of parameters for the black hole, the intersection of the black hole with the brane approximates a Banados-Teitelboim-Zanelli (BTZ) black hole on the brane with corrections that fall off exponentially outside the horizon. We compute the quasinormal modes of the braneworld black hole, and compare them to the known quasinormal modes of the three-dimensional BTZ black hole. We find that there are two distinct regions for the braneworld black hole solutions that are reflected in the dependence of the quasinormal modes on the black hole mass. The imaginary parts of the quasinormal modes display phenomenological similarities to the quasinormal modes of the three-dimensional BTZ black hole, indicating that nonlinear gravitational effects may not be enough to distinguish between a lower-dimensional theory and a theory derived from a higher-dimensional braneworld. Secondly, we consider the evolution of non-extremal black holes in N=4, d=2 supergravity, and investigate how such black holes might evolve over time if perturbed away from extremality. We study this problem in the probe limit by finding tunneling amplitudes for a Dirac field in a single-centered background, which gives the decay rates for the emission of charged probe black holes from the central black hole. We find that there is no minimum to the potential for the probe particles at a finite distance from the central black hole, so any probes that are emitted escape to infinity. If
Boson shells harboring charged black holes
Kleihaus, Burkhard; Kunz, Jutta; Laemmerzahl, Claus; List, Meike
2010-11-15
We consider boson shells in scalar electrodynamics coupled to Einstein gravity. The interior of the shells can be empty space, or harbor a black hole or a naked singularity. We analyze the properties of these types of solutions and determine their domains of existence. We investigate the energy conditions and present mass formulae for the composite black hole-boson shell systems. We demonstrate that these types of solutions violate black hole uniqueness.
Begelman, Mitchell C
2003-06-20
Black holes are common objects in the universe. Each galaxy contains large numbers-perhaps millions-of stellar-mass black holes, each the remnant of a massive star. In addition, nearly every galaxy contains a supermassive black hole at its center, with a mass ranging from millions to billions of solar masses. This review discusses the demographics of black holes, the ways in which they interact with their environment, factors that may regulate their formation and growth, and progress toward determining whether these objects really warp spacetime as predicted by the general theory of relativity. PMID:12817138
Information loss in black holes
NASA Astrophysics Data System (ADS)
Hawking, S. W.
2005-10-01
The question of whether information is lost in black holes is investigated using Euclidean path integrals. The formation and evaporation of black holes is regarded as a scattering problem with all measurements being made at infinity. This seems to be well formulated only in asymptotically AdS spacetimes. The path integral over metrics with trivial topology is unitary and information preserving. On the other hand, the path integral over metrics with nontrivial topologies leads to correlation functions that decay to zero. Thus at late times only the unitary information preserving path integrals over trivial topologies will contribute. Elementary quantum gravity interactions do not lose information or quantum coherence.
Black hole mimickers: Regular versus singular behavior
Lemos, Jose P. S.; Zaslavskii, Oleg B.
2008-07-15
Black hole mimickers are possible alternatives to black holes; they would look observationally almost like black holes but would have no horizon. The properties in the near-horizon region where gravity is strong can be quite different for both types of objects, but at infinity it could be difficult to discern black holes from their mimickers. To disentangle this possible confusion, we examine the near-horizon properties, and their connection with far away asymptotic properties, of some candidates to black mimickers. We study spherically symmetric uncharged or charged but nonextremal objects, as well as spherically symmetric charged extremal objects. Within the uncharged or charged but nonextremal black hole mimickers, we study nonextremal {epsilon}-wormholes on the threshold of the formation of an event horizon, of which a subclass are called black foils, and gravastars. Within the charged extremal black hole mimickers we study extremal {epsilon}-wormholes on the threshold of the formation of an event horizon, quasi-black holes, and wormholes on the basis of quasi-black holes from Bonnor stars. We elucidate whether or not the objects belonging to these two classes remain regular in the near-horizon limit. The requirement of full regularity, i.e., finite curvature and absence of naked behavior, up to an arbitrary neighborhood of the gravitational radius of the object enables one to rule out potential mimickers in most of the cases. A list ranking the best black hole mimickers up to the worst, both nonextremal and extremal, is as follows: wormholes on the basis of extremal black holes or on the basis of quasi-black holes, quasi-black holes, wormholes on the basis of nonextremal black holes (black foils), and gravastars. Since in observational astrophysics it is difficult to find extremal configurations (the best mimickers in the ranking), whereas nonextremal configurations are really bad mimickers, the task of distinguishing black holes from their mimickers seems to
Black Holes Shed Light on Galaxy Formation
NASA Technical Reports Server (NTRS)
2000-01-01
This videotape is comprised of several segments of animations on black holes and galaxy formation, and several segments of an interview with Dr. John Kormendy. The animation segments are: (1) a super massive black hole, (2) Centarus A active black hole found in a collision, (3) galaxy NGC-4261 (active black hole and jet model), (4) galaxy M-32 (orbits of stars are effected by the gravity of the black hole), (5) galaxy M-37 (motion of stars increases as mass of black hole increases), (6) Birth of active galactic nuclei, (7) the collision of two galaxy leads to merger of the black holes, (8) Centarus A and simulation of the collision of 2 galaxies. There are also several segments of an interview with John Kormendy. In these segments he discusses the two most important aspects of his recent black hole work: (1) the correlations between galaxies speed and the mass of the black holes, and (2) the existence of black holes and galactic formation. He also discusses the importance of the Hubble Space Telescope and the Space Telescope Imaging Spectrograph to the study of black holes. He also shows the methodology of processing images from the spectrograph in his office.
Noncommutative Singular Black Holes
NASA Astrophysics Data System (ADS)
Hamid Mehdipour, S.
2010-11-01
In this paper, applying the method of coordinate coherent states to describe a noncommutative model of Vaidya black holes leads to an exact (t — r) dependence of solution in terms of the noncommutative parameter σ. In this setup, there is no black hole remnant at long times.
NASA Astrophysics Data System (ADS)
Bousso, R.; Hawking, S. W.
1997-08-01
We summarise recent work on the quantum production of black holes in the inflationary era. We describe, in simple terms, the Euclidean approach used, and the results obtained both for the pair creation rate and for the evolution of the black holes.
Scrambling with matrix black holes
NASA Astrophysics Data System (ADS)
Brady, Lucas; Sahakian, Vatche
2013-08-01
If black holes are not to be dreaded sinks of information but rather fully described by unitary evolution, they must scramble in-falling data and eventually leak it through Hawking radiation. Sekino and Susskind have conjectured that black holes are fast scramblers; they generate entanglement at a remarkably efficient rate, with the characteristic time scaling logarithmically with the entropy. In this work, we focus on Matrix theory—M-theory in the light-cone frame—and directly probe the conjecture. We develop a concrete test bed for quantum gravity using the fermionic variables of Matrix theory and show that the problem becomes that of chains of qubits with an intricate network of interactions. We demonstrate that the black hole system evolves much like a Brownian quantum circuit, with strong indications that it is indeed a fast scrambler. We also analyze the Berenstein-Maldacena-Nastase model and reach the same tentative conclusion.
Fluctuating black hole horizons
NASA Astrophysics Data System (ADS)
Mei, Jianwei
2013-10-01
In this paper we treat the black hole horizon as a physical boundary to the spacetime and study its dynamics following from the Gibbons-Hawking-York boundary term. Using the Kerr black hole as an example we derive an effective action that describes, in the large wave number limit, a massless Klein-Gordon field living on the average location of the boundary. Complete solutions can be found in the small rotation limit of the black hole. The formulation suggests that the boundary can be treated in the same way as any other matter contributions. In particular, the angular momentum of the boundary matches exactly with that of the black hole, suggesting an interesting possibility that all charges (including the entropy) of the black hole are carried by the boundary. Using this as input, we derive predictions on the Planck scale properties of the boundary.
Entropy spectrum of dimensional stringy black holes
NASA Astrophysics Data System (ADS)
Suresh, Jishnu; Kuriakose, V. C.
2015-05-01
We explore the entropy spectrum of dimensional dilatonic stringy black holes via the adiabatic invariant integral method known as Jiang and Han's method (Phys Lett B 718:584, 2012) and the Bohr-Sommerfeld quantization rule. It is found that the corresponding spectrum depends on black hole parameters like charge, ADM mass, and, more interestingly, on the dilatonic field. We calculate the entropy of the present black hole system via the Euclidean treatment of quantum gravity and study the thermodynamics of the black hole and find that the system does not undergo any phase transition.
Black hole thermodynamics from Euclidean horizon constraints.
Carlip, S
2007-07-13
To explain black hole thermodynamics in quantum gravity, one must introduce constraints to ensure that a black hole is actually present. I show that for a large class of black holes, such "horizon constraints" allow the use of conformal field theory techniques to compute the density of states, reproducing the Bekenstein-Hawking entropy in a nearly model-independent manner. One standard string theory approach to black hole entropy arises as a special case, lending support to the claim that the mechanism may be "universal." I argue that the relevant degrees of freedom are Goldstone-boson-like excitations arising from the weak breaking of symmetry by the constraints. PMID:17678209
Erratic Black Hole Regulates Itself
NASA Astrophysics Data System (ADS)
2009-03-01
't entirely understand, the other one gets the upper hand." GRS 1915+105 Chandra X-ray Image of GRS 1915+105 The latest Chandra results also show that the wind and the jet carry about the same amount of matter away from the black hole. This is evidence that the black hole is somehow regulating its accretion rate, which may be related to the toggling between mass expulsion via either a jet or a wind from the accretion disk. Self-regulation is a common topic when discussing supermassive black holes, but this is the first clear evidence for it in stellar-mass black holes. "It is exciting that we may be on the track of explaining two mysteries at the same time: how black hole jets can be shut down and also how black holes regulate their growth," said co-author Julia Lee, assistant professor in the Astronomy department at the Harvard-Smithsonian Center for Astrophysics. "Maybe black holes can regulate themselves better than the financial markets!" Although micro-quasars and quasars differ in mass by factors of millions, they should show a similarity in behavior when their very different physical scales are taken into account. People Who Read This Also Read... Chandra Data Reveal Rapidly Whirling Black Holes Jet Power and Black Hole Assortment Revealed in New Chandra Image Celebrate the International Year of Astronomy Ghost Remains After Black Hole Eruption "If quasars and micro-quasars behave very differently, then we have a big problem to figure out why, because gravity treats them the same," said Neilsen. "So, our result is actually very reassuring, because it's one more link between these different types of black holes." The timescale for changes in behavior of a black hole should vary in proportion to the mass. For example, an hour-long timescale for changes in GRS 1915 would correspond to about 10,000 years for a supermassive black hole that weighs a billion times the mass of the Sun. "We cannot hope to explore at this level of detail in any single supermassive black hole
Some aspects of virtual black holes
Faizal, M.
2012-03-15
We first consider consistently third-quantize modified gravity. We then analyze certain aspects of virtual black holes in this third-quantized modified gravity. We see how a statistical mechanical origin for the Bekenstein-Hawking entropy naturally arises in this model. Furthermore, the area and hence the entropy of a real macroscopic black hole is quantized in this model. Virtual black holes cause a loss of quantum coherence, which gives an intrinsic entropy to all physical systems that can be used to define a direction of time and hence provide a solution to the problem of time.
Renormalized vacuum polarization of rotating black holes
NASA Astrophysics Data System (ADS)
Ferreira, Hugo R. C.
2015-04-01
Quantum field theory on rotating black hole spacetimes is plagued with technical difficulties. Here, we describe a general method to renormalize and compute the vacuum polarization of a quantum field in the Hartle-Hawking state on rotating black holes. We exemplify the technique with a massive scalar field on the warped AdS3 black hole solution to topologically massive gravity, a deformation of (2 + 1)-dimensional Einstein gravity. We use a "quasi-Euclidean" technique, which generalizes the Euclidean techniques used for static spacetimes, and we subtract the divergences by matching to a sum over mode solutions on Minkowski spacetime. This allows us, for the first time, to have a general method to compute the renormalized vacuum polarization, for a given quantum state, on a rotating black hole, such as the physically relevant case of the Kerr black hole in four dimensions.
Entropy, area, and black hole pairs
NASA Astrophysics Data System (ADS)
Hawking, S. W.; Horowitz, Gary T.; Ross, Simon F.
1995-04-01
We clarify the relation between gravitational entropy and the area of horizons. We first show that the entropy of an extreme Reissner-Nordström black hole is zero, despite the fact that its horizon has nonzero area. Next, we consider the pair creation of extremal and nonextremal black holes. It is shown that the action which governs the rate of this pair creation is directly related to the area of the acceleration horizon and (in the nonextremal case) the area of the black hole event horizon. This provides a simple explanation of the result that the rate of pair creation of nonextreme black holes is enhanced by precisely the black hole entropy. Finally, we discuss black hole annihilation, and argue that Planck scale remnants are not sufficient to preserve unitarity in quantum gravity.
Escape of Black Holes from the Brane
Flachi, Antonino; Tanaka, Takahiro
2005-10-14
TeV-scale gravity theories allow the possibility of producing small black holes at energies that soon will be explored at the CERN LHC or at the Auger observatory. One of the expected signatures is the detection of Hawking radiation that might eventually terminate if the black hole, once perturbed, leaves the brane. Here, we study how the 'black hole plus brane' system evolves once the black hole is given an initial velocity that mimics, for instance, the recoil due to the emission of a graviton. The results of our dynamical analysis show that the brane bends around the black hole, suggesting that the black hole eventually escapes into the extra dimensions once two portions of the brane come in contact and reconnect. This gives a dynamical mechanism for the creation of baby branes.
ULTRAMASSIVE BLACK HOLE COALESCENCE
Khan, Fazeel Mahmood; Holley-Bockelmann, Kelly; Berczik, Peter E-mail: k.holley@vanderbilt.edu
2015-01-10
Although supermassive black holes (SMBHs) correlate well with their host galaxies, there is an emerging view that outliers exist. Henize 2-10, NGC 4889, and NGC 1277 are examples of SMBHs at least an order of magnitude more massive than their host galaxy suggests. The dynamical effects of such ultramassive central black holes is unclear. Here, we perform direct N-body simulations of mergers of galactic nuclei where one black hole is ultramassive to study the evolution of the remnant and the black hole dynamics in this extreme regime. We find that the merger remnant is axisymmetric near the center, while near the large SMBH influence radius, the galaxy is triaxial. The SMBH separation shrinks rapidly due to dynamical friction, and quickly forms a binary black hole; if we scale our model to the most massive estimate for the NGC 1277 black hole, for example, the timescale for the SMBH separation to shrink from nearly a kiloparsec to less than a parsec is roughly 10 Myr. By the time the SMBHs form a hard binary, gravitational wave emission dominates, and the black holes coalesce in a mere few Myr. Curiously, these extremely massive binaries appear to nearly bypass the three-body scattering evolutionary phase. Our study suggests that in this extreme case, SMBH coalescence is governed by dynamical friction followed nearly directly by gravitational wave emission, resulting in a rapid and efficient SMBH coalescence timescale. We discuss the implications for gravitational wave event rates and hypervelocity star production.
Psaltis, Dimitrios
2007-05-01
In braneworld gravity models with a finite anti-de Sitter space (AdS) curvature in the extra dimension, the AdS/conformal field theory correspondence leads to a prediction for the lifetime of astrophysical black holes that is significantly smaller than the Hubble time, for asymptotic curvatures that are consistent with current experiments. Using the recent measurements of the position, three-dimensional spatial velocity, and mass of the black hole XTE J1118+480, I calculate a lower limit on its kinematic age of > or =11 Myr (95% confidence). This translates into an upper limit for the asymptotic AdS curvature in the extra dimensions of <0.08 mm, which significantly improves the limit obtained by table top experiments of sub mm gravity. PMID:17501556
Shapes of rotating nonsingular black hole shadows
NASA Astrophysics Data System (ADS)
Amir, Muhammed; Ghosh, Sushant G.
2016-07-01
It is believed that curvature singularities are a creation of general relativity and, hence, in the absence of a quantum gravity, models of nonsingular black holes have received significant attention. We study the shadow (apparent shape), an optical appearance because of its strong gravitational field, cast by a nonsingular black hole which is characterized by three parameters, i.e., mass (M ), spin (a ), and a deviation parameter (k ). The nonsingular black hole under consideration is a generalization of the Kerr black hole that can be recognized asymptotically (r ≫k ,k >0 ) explicitly as the Kerr-Newman black hole, and in the limit k →0 as the Kerr black hole. It turns out that the shadow of a nonsingular black hole is a dark zone covered by a deformed circle. Interestingly, it is seen that the shadow of a black hole is affected due to the parameter k . Indeed, for a given a , the size of a shadow reduces as the parameter k increases, and the shadow becomes more distorted as we increase the value of the parameter k when compared with the analogous Kerr black hole shadow. We also investigate, in detail, how the ergoregion of a black hole is changed due to the deviation parameter k .
Black hole evaporation rates without spacetime.
Braunstein, Samuel L; Patra, Manas K
2011-08-12
Verlinde recently suggested that gravity, inertia, and even spacetime may be emergent properties of an underlying thermodynamic theory. This vision was motivated in part by Jacobson's 1995 surprise result that the Einstein equations of gravity follow from the thermodynamic properties of event horizons. Taking a first tentative step in such a program, we derive the evaporation rate (or radiation spectrum) from black hole event horizons in a spacetime-free manner. Our result relies on a Hilbert space description of black hole evaporation, symmetries therein which follow from the inherent high dimensionality of black holes, global conservation of the no-hair quantities, and the existence of Penrose processes. Our analysis is not wedded to standard general relativity and so should apply to extended gravity theories where we find that the black hole area must be replaced by some other property in any generalized area theorem. PMID:21902381
NASA Astrophysics Data System (ADS)
Emparan, Roberto; Figueras, Pau; Martínez, Marina
2014-12-01
We study six-dimensional rotating black holes with bumpy horizons: these are topologically spherical, but the sizes of symmetric cycles on the horizon vary nonmonotonically with the polar angle. We construct them numerically for the first three bumpy families, and follow them in solution space until they approach critical solutions with localized singularities on the horizon. We find strong evidence of the conical structures that have been conjectured to mediate the transitions to black rings, to black Saturns, and to a novel class of bumpy black rings. For a different, recently identified class of bumpy black holes, we find evidence that this family ends in solutions with a localized singularity that exhibits apparently universal properties, and which does not seem to allow for transitions to any known class of black holes.
NASA Astrophysics Data System (ADS)
Garmire, Gordon
1999-09-01
WE PROPOSE TO CARRY OUT A SYSTEMATIC STUDY OF EMISSION AND ABSORPTION SPECTRAL FEATURES THAT ARE OFTEN SEEN IN X-RAY SPECTRA OF BLACK HOLE BINARIES. THE EXCELLENT SENSITIVITY AND ENERGY RESOLUTION OF THE ACIS/HETG COMBINATION WILL NOT ONLY HELP RESOLVE AMBIGUITIES IN INTERPRETING THESE FEATURES, BUT MAY ALLOW MODELLING OF THE EMISSION LINE PROFILES IN DETAIL. THE PROFILES MAY CONTAIN INFORMATION ON SUCH FUNDAMENTAL PROPERTIES AS THE SPIN OF BLACK HOLES. THEREFORE, THIS STUDY COULD LEAD TO A MEASUREMENT OF BLACK HOLE SPIN FOR SELECTED SOURCES. THE RESULT CAN THEN BE DIRECTLY COMPARED WITH THOSE FROM PREVIOUS STUDIES BASED ON INDEPENDENT METHODS.
Hansen, Jakob; Yeom, Dong-han
2015-09-07
We investigate the relation between the existence of mass inflation and model parameters of string-inspired gravity models. In order to cover various models, we investigate a Brans-Dicke theory that is coupled to a U(1) gauge field. By tuning a model parameter that decides the coupling between the Brans-Dicke field and the electromagnetic field, we can make both of models such that the Brans-Dicke field is biased toward strong or weak coupling directions after gravitational collapses. We observe that as long as the Brans-Dicke field is biased toward any (strong or weak) directions, there is no Cauchy horizon and no mass inflation. Therefore, we conclude that to induce a Cauchy horizon and mass inflation inside a charged black hole, either there is no bias of the Brans-Dicke field as well as no Brans-Dicke hair outside the horizon or such a biased Brans-Dicke field should be well trapped and controlled by a potential.
Erratic Black Hole Regulates Itself
NASA Astrophysics Data System (ADS)
2009-03-01
't entirely understand, the other one gets the upper hand." GRS 1915+105 Chandra X-ray Image of GRS 1915+105 The latest Chandra results also show that the wind and the jet carry about the same amount of matter away from the black hole. This is evidence that the black hole is somehow regulating its accretion rate, which may be related to the toggling between mass expulsion via either a jet or a wind from the accretion disk. Self-regulation is a common topic when discussing supermassive black holes, but this is the first clear evidence for it in stellar-mass black holes. "It is exciting that we may be on the track of explaining two mysteries at the same time: how black hole jets can be shut down and also how black holes regulate their growth," said co-author Julia Lee, assistant professor in the Astronomy department at the Harvard-Smithsonian Center for Astrophysics. "Maybe black holes can regulate themselves better than the financial markets!" Although micro-quasars and quasars differ in mass by factors of millions, they should show a similarity in behavior when their very different physical scales are taken into account. People Who Read This Also Read... Chandra Data Reveal Rapidly Whirling Black Holes Jet Power and Black Hole Assortment Revealed in New Chandra Image Celebrate the International Year of Astronomy Ghost Remains After Black Hole Eruption "If quasars and micro-quasars behave very differently, then we have a big problem to figure out why, because gravity treats them the same," said Neilsen. "So, our result is actually very reassuring, because it's one more link between these different types of black holes." The timescale for changes in behavior of a black hole should vary in proportion to the mass. For example, an hour-long timescale for changes in GRS 1915 would correspond to about 10,000 years for a supermassive black hole that weighs a billion times the mass of the Sun. "We cannot hope to explore at this level of detail in any single supermassive black hole
NASA Astrophysics Data System (ADS)
Barr, Ian A.; Bull, Anne; O’Brien, Eileen; Drillsma-Milgrom, Katy A.; Milgrom, Lionel R.
2016-07-01
Two-dimensional shadows formed by illuminating vortices are shown to be visually analogous to the gravitational action of black holes on light and surrounding matter. They could be useful teaching aids demonstrating some of the consequences of general relativity.
ERIC Educational Resources Information Center
Ruffini, Remo; Wheeler, John A.
1971-01-01
discusses the cosmology theory of a black hole, a region where an object loses its identity, but mass, charge, and momentum are conserved. Include are three possible formation processes, theorized properties, and three way they might eventually be detected. (DS)
Holographic interpretation of acoustic black holes
NASA Astrophysics Data System (ADS)
Ge, Xian-Hui; Sun, Jia-Rui; Tian, Yu; Wu, Xiao-Ning; Zhang, Yun-Long
2015-10-01
With the attempt to find the holographic description of the usual acoustic black holes in fluid, we construct an acoustic black hole formed in the d -dimensional fluid located at the timelike cutoff surface of a neutral black brane in asymptotically AdSd +1 spacetime; the bulk gravitational dual of the acoustic black hole is presented at the first order of the hydrodynamic fluctuation. Moreover, the Hawking-like temperature of the acoustic black hole horizon is showed to be connected to the Hawking temperature of the real anti-de Sitter (AdS) black brane in the bulk, and the duality between the phonon scattering in the acoustic black hole and the sound channel quasinormal mode propagating in the bulk perturbed AdS black brane is extracted. We thus point out that the acoustic black hole appearing in fluid, which was originally proposed as an analogous model to simulate Hawking radiation of the real black hole, is not merely an analogy, it can indeed be used to describe specific properties of the real AdS black holes, in the spirit of the fluid/gravity duality.
Asymptotically flat black holes in 2 +1 dimensions
NASA Astrophysics Data System (ADS)
Alkaç, Gökhan; Kilicarslan, Ercan; Tekin, Bayram
2016-04-01
Asymptotically flat black holes in 2 +1 dimensions are a rarity. We study the recently found black flower solutions (asymptotically flat black holes with deformed horizons), static black holes, rotating black holes and the dynamical black flowers (black holes with radiative gravitons) of the purely quadratic version of new massive gravity. We show how they appear in this theory and we also show that they are also solutions to the infinite order extended version of the new massive gravity, that is the Born-Infeld extension of new massive gravity with an amputated Einsteinian piece. The same metrics also solve the topologically extended versions of these theories, with modified conserved charges and the thermodynamical quantities, such as the Wald entropy. Besides these we find new conformally flat radiating type solutions to these extended gravity models. We also show that these metrics do not arise in Einstein's gravity coupled to physical perfect fluids.
NASA Astrophysics Data System (ADS)
Babichev, Eugeny; Charmousis, Christos; Hassaine, Mokhtar
2015-05-01
We consider an Abelian gauge field coupled to a particular truncation of Horndeski theory. The Galileon field has translation symmetry and couples non minimally both to the metric and the gauge field. When the gauge-scalar coupling is zero the gauge field reduces to a standard Maxwell field. By taking into account the symmetries of the action, we construct charged black hole solutions. Allowing the scalar field to softly break symmetries of spacetime we construct black holes where the scalar field is regular on the black hole event horizon. Some of these solutions can be interpreted as the equivalent of Reissner-Nordstrom black holes of scalar tensor theories with a non trivial scalar field. A self tuning black hole solution found previously is extended to the presence of dyonic charge without affecting whatsoever the self tuning of a large positive cosmological constant. Finally, for a general shift invariant scalar tensor theory we demonstrate that the scalar field Ansatz and method we employ are mathematically compatible with the field equations. This opens up the possibility for novel searches of hairy black holes in a far more general setting of Horndeski theory.
NASA Technical Reports Server (NTRS)
Garcia, M.
1998-01-01
Our UV/VIS work concentrates on black hole X-ray nova. These objects consist of two stars in close orbit, one of which we believe is a black hole - our goal is to SHOW that one is a black hole. In order to reach this goal we carry out observations in the Optical, UV, IR and X-ray bands, and compare the observations to theoretical models. In the past year, our UV/VIS grant has provided partial support (mainly travel funds and page charges) for work we have done on X-ray nova containing black holes and neutron stars. We have been very successful in obtaining telescope time to support our project - we have completed approximately a dozen separate observing runs averaging 3 days each, using the MMT (5M), Lick 3M, KPNO 2.1M, CTIO 4M, CTIO 1.5M, and the SAO/WO 1.2M telescopes. These observations have allowed the identification of one new black hole (Nova Oph 1977), and allowed the mass of another to be measured (GS2000+25). Perhaps our most exciting new result is the evidence we have gathered for the existence of 'event horizons' in black hole X-ray nova.
ERIC Educational Resources Information Center
Science Teacher, 2005
2005-01-01
Scientists using NASA's Swift satellite say they have found newborn black holes, just seconds old, in a confused state of existence. The holes are consuming material falling into them while somehow propelling other material away at great speeds. "First comes a blast of gamma rays followed by intense pulses of x-rays. The energies involved are much…
Black holes in loop quantum gravity: the complete space-time.
Gambini, Rodolfo; Pullin, Jorge
2008-10-17
We consider the quantization of the complete extension of the Schwarzschild space-time using spherically symmetric loop quantum gravity. We find an exact solution corresponding to the semiclassical theory. The singularity is eliminated but the space-time still contains a horizon. Although the solution is known partially numerically and therefore a proper global analysis is not possible, a global structure akin to a singularity-free Reissner-Nordström space-time including a Cauchy horizon is suggested. PMID:18999656
Extended solution space for Chern-Simons gravity: The slowly rotating Kerr black hole
Cambiaso, Mauro; Urrutia, Luis F.
2010-11-15
In the Einstein-Cartan formulation, an iterative procedure to find solutions in nondynamical Chern-Simons gravity in vacuum is proposed. The iterations, in powers of a small parameter {beta} which codifies the Chern-Simons coupling, start from an arbitrary torsionless solution of Einstein equations. With Schwarzschild as the zeroth-order choice, we derive a second-order differential equation for the O({beta}) corrections to the metric, for an arbitrary zeroth-order embedding parameter. In particular, the slowly rotating Kerr metric is an O({beta}) solution in either the canonical or the axial embeddings.
'Black holes': escaping the void.
Waldron, Sharn
2013-02-01
The 'black hole' is a metaphor for a reality in the psyche of many individuals who have experienced complex trauma in infancy and early childhood. The 'black hole' has been created by an absence of the object, the (m)other, so there is no internalized object, no (m)other in the psyche. Rather, there is a 'black hole' where the object should be, but the infant is drawn to it, trapped by it because of an intrinsic, instinctive need for a 'real object', an internalized (m)other. Without this, the infant cannot develop. It is only the presence of a real object that can generate the essential gravity necessary to draw the core of the self that is still in an undeveloped state from deep within the abyss. It is the moving towards a real object, a (m)other, that relativizes the absolute power of the black hole and begins a reformation of its essence within the psyche. PMID:23351000
Rotating black holes at future colliders. III. Determination of black hole evolution
Ida, Daisuke; Oda, Kin-ya; Park, Seong Chan
2006-06-15
TeV scale gravity scenario predicts that the black hole production dominates over all other interactions above the scale and that the Large Hadron Collider will be a black hole factory. Such higher-dimensional black holes mainly decay into the standard model fields via the Hawking radiation whose spectrum can be computed from the greybody factor. Here we complete the series of our work by showing the greybody factors and the resultant spectra for the brane-localized spinor and vector field emissions for arbitrary frequencies. Combining these results with the previous works, we determine the complete radiation spectra and the subsequent time evolution of the black hole. We find that, for a typical event, well more than half a black hole mass is emitted when the hole is still highly rotating, confirming our previous claim that it is important to take into account the angular momentum of black holes.
NASA Astrophysics Data System (ADS)
Bak, Dongsu; Gutperle, Michael; Janik, Romuald A.
2011-10-01
In this paper Janus black holes in A dS 3 are considered. These are static solutions of an Einstein-scalar system with broken translation symmetry along the horizon. These solutions are dual to interface conformal field theories at finite temperature. An approximate solution is first constructed using perturbation theory around a planar BTZ blackhole. Numerical and exact solutions valid for all sets of parameters are then found and compared. Using the exact solution the thermodynamics of the system is analyzed. The entropy associated with the Janus black hole is calculated and it is found that the entropy of the black Janus is the sum of the undeformed black hole entropy and the entanglement entropy associated with the defect.
Black hole based tests of general relativity
NASA Astrophysics Data System (ADS)
Yagi, Kent; Stein, Leo C.
2016-03-01
General relativity has passed all solar system experiments and neutron star based tests, such as binary pulsar observations, with flying colors. A more exotic arena for testing general relativity is in systems that contain one or more black holes. Black holes are the most compact objects in the Universe, providing probes of the strongest-possible gravitational fields. We are motivated to study strong-field gravity since many theories give large deviations from general relativity only at large field strengths, while recovering the weak-field behavior. In this article, we review how one can probe general relativity and various alternative theories of gravity by using electromagnetic waves from a black hole with an accretion disk, and gravitational waves from black hole binaries. We first review model-independent ways of testing gravity with electromagnetic/gravitational waves from a black hole system. We then focus on selected examples of theories that extend general relativity in rather simple ways. Some important characteristics of general relativity include (but are not limited to) (i) only tensor gravitational degrees of freedom, (ii) the graviton is massless, (iii) no quadratic or higher curvatures in the action, and (iv) the theory is four-dimensional. Altering a characteristic leads to a different extension of general relativity: (i) scalar-tensor theories, (ii) massive gravity theories, (iii) quadratic gravity, and (iv) theories with large extra dimensions. Within each theory, we describe black hole solutions, their properties, and current and projected constraints on each theory using black hole based tests of gravity. We close this review by listing some of the open problems in model-independent tests and within each specific theory.
Aspects of Black Holes in Higher Dimensions
NASA Astrophysics Data System (ADS)
Hartnett, Gavin S.
This thesis is divided into three Parts. In Part I the general theory of black holes in higher dimensions is discussed. In addition to an introductory essay, two studies of linear perturbations of Myers-Perry black holes are presented. These black holes are the higher dimensional generalization of the Kerr black hole, and their analysis reveals numerous instabilities. Threshold unstable modes provide the connection between the Myers-Perry black holes and novel stationary black hole solutions such as black rings or black Saturns, as well as other non-stationary solutions known as single Killing vector field black holes. In Part II gauge/gravity duality is briefly reviewed and two aspects are studied in detail. First, the problem of finding a holographic dual to a superconductor with d-wave order parameter is investigated, and second, we examine the problem of holographic thermalization in field theories dual to rotating black holes. Lastly, in Part III the role of de Sitter solutions in string theory is discussed. A recent puzzle surrounding the fate of the de Sitter landscape is reviewed, and it is shown how the study of black holes in certain flux backgrounds can provide insight into this puzzle. We then present a theorem ruling out the addition of black holes to a certain class of flux backgrounds. Finally, a study is presented which shows that black holes can be added to the flux backgrounds relevant for the de Sitter landscape in string theory, thereby providing strong evidence for the resolution of the puzzle.
NASA Astrophysics Data System (ADS)
Genzel, Reinhard
1998-01-01
The dimness of the black holes located at the center of galaxies surprises astrophysicists, but a possible explanation has been found in the behavior of the plasma they consume. In a hot accretion flow, the gas is ionized to form a plasma. The heavy ions carry most of the mass, and thus of the energy, whereas the electrons produce most of the radiation. But, crucially, in a low-density flow the temperatures of the ions and of the electrons may decouple. Consequently, most of the gravitational energy would be viscously converted into thermal energy of the ions and not radiated away by the electrons. Instead, the gravitational energy is carried with the flow across the event horizon of the black hole. Such a flow leads to a low radiation efficiency even in a highly dissipative accretion disk.
Kerr Black Hole Entropy and its Quantization
NASA Astrophysics Data System (ADS)
Jiang, Ji-Jian; Li, Chuan-An; Cheng, Xie-Feng
2016-08-01
By constructing the four-dimensional phase space based on the observable physical quantity of Kerr black hole and gauge transformation, the Kerr black hole entropy in the phase space was obtained. Then considering the corresponding mechanical quantities as operators and making the operators quantized, entropy spectrum of Kerr black hole was obtained. Our results show that the Kerr black hole has the entropy spectrum with equal intervals, which is in agreement with the idea of Bekenstein. In the limit of large event horizon, the area of the adjacent event horizon of the black hole have equal intervals. The results are in consistent with the results based on the loop quantum gravity theory by Dreyer et al.
Key problems in black hole physics today
NASA Astrophysics Data System (ADS)
Joshi, Pankaj S.
2011-12-01
We review here some of the major open issues and challenges in black hole physics today, and the current progress on the same. It is pointed out that to secure a concrete foundation for the basic theory as well as astrophysical applications for black hole physics, it is essential to gain a suitable insight into these questions. In particular, we discuss the recent results investigating the final fate of a massive star within the framework of the Einstein gravity, and the stability and genericity aspects of the gravitational collapse outcomes in terms of black holes and naked singularities. Recent developments such as spinning up a black hole by throwing matter into it, and physical effects near naked singularities are considered. It is pointed out that some of the new results obtained in recent years in the theory of gravitational collapse imply interesting possibilities and understanding for the theoretical advances in gravity as well as towards new astrophysical applications.
Key problems in black hole physics today
NASA Astrophysics Data System (ADS)
Joshi, Pankaj S.
2011-03-01
We review here some of the major open issues and challenges in black hole physics today, and the current progress on the same. It is pointed out that to secure a concrete foundation for the basic theory as well as astrophysical applications for black hole physics, it is essential to gain a suitable insight into these questions. In particular, we discuss the recent results investigating the final fate of a massive star within the framework of the Einstein gravity, and the stability and genericity aspects of the gravitational collapse outcomes in terms of black holes and naked singularities. Recent developments such as spinning up a black hole by throwing matter into it, and physical effects near naked singularities are considered. It is pointed out that some of the new results obtained in recent years in the theory of gravitational collapse imply interesting possibilities and understanding for the theoretical advances in gravity as well as towards new astrophysical applications.
Problems of Construction of Black Holes and Traversed Wormholes in Various Theories of Gravity
NASA Astrophysics Data System (ADS)
Karbanovski, Valeri; Kairov, Taimuraz.; Melehina, Olga
In the framework of general relativity found new vacuum solutions [1,2] for the spherically symmetric non-static metrics as a constant source ("dynamic analog" gravitational radius), and a source in the form of time-dependent functions. In the latter case, the conditions for a smooth cross-linking with the original static metric. Within Post-Einstein theory of gravitation (PETG, [3]), is consider the variant with zero scalar curvature of space-time is considered. Found external solutions for spherically symmetric objects that allow a smooth stitching at distances slightly exceeding the gravitational radius of the source. We also show that in the studied approach the traversable vacuum wormholes can not be realized. In the theory of gravity with vacuum polarization (TGVP, [4]) built vacuum static spherically symmetric nonsingular solutions. At this the "polarization effects" appear only under the gravitational radius of the source. Also obtained metric describing the vacuum traversable wormhole. References begin{enumerate} Karbanovski V.V. et. al. - JETP, 2012, Vol. 115, No. 2, pp. 208-211. Karbanovski V.V. et. al. - JETP, 2012, Vol. 115, No. 4, pp. 733. Karbanovski V.V. et. al. - Class. Quantum Grav., 2012, Vol. 29, No. 6, 065007. Karbanovski V.V. et. al. - Acta Phys. Pol. B, 2011, Vol. 42, No.1, p. 171.
NASA Astrophysics Data System (ADS)
Hawking, S. W.
1996-03-01
One would expect spacetime to have a foamlike structure on the Planck scale with a very high topology. If spacetime is simply connected (which is assumed in this paper), the nontrivial homology occurs in dimension two, and spacetime can be regarded as being essentially the topological sum of S2×S2 and K3 bubbles. Comparison with the instantons for pair creation of black holes shows that the S2×S2 bubbles can be interpreted as closed loops of virtual black holes. It is shown that scattering in such topological fluctuations leads to loss of quantum coherence, or in other words, to a superscattering matrix S/ that does not factorize into an S matrix and its adjoint. This loss of quantum coherence is very small at low energies for everything except scalar fields, leading to the prediction that we may never observe the Higgs particle. Another possible observational consequence may be that the θ angle of QCD is zero without having to invoke the problematical existence of a light axion. The picture of virtual black holes given here also suggests that macroscopic black holes will evaporate down to the Planck size and then disappear in the sea of virtual black holes.
Black holes in magnetic monopoles
NASA Technical Reports Server (NTRS)
Lee, Kimyeong; Nair, V. P.; Weinberg, Erick J.
1991-01-01
We study magnetically charged classical solutions of a spontaneously broken gauge theory interacting with gravity. We show that nonsingular monopole solutions exist only if the Higgs field vacuum expectation value v is less than or equal to a critical value v sub cr, which is of the order of the Planck mass. In the limiting case, the monopole becomes a black hole, with the region outside the horizon described by the critical Reissner-Nordstrom solution. For v less than v sub cr, we find additional solutions which are singular at f = 0, but which have this singularity hidden within a horizon. These have nontrivial matter fields outside the horizon, and may be interpreted as small black holes lying within a magnetic monopole. The nature of these solutions as a function of v and of the total mass M and their relation to the Reissner-Nordstrom solutions is discussed.
Local temperature for dynamical black holes
NASA Astrophysics Data System (ADS)
Hayward, Sean A.; di Criscienzo, R.; Nadalini, M.; Vanzo, L.; Zerbini, S.
2009-05-01
A local Hawking temperature was recently derived for any future outer trapping horizon in spherical symmetry, using a Hamilton-Jacobi tunneling method, and is given by a dynamical surface gravity as defined geometrically. Descriptions are given of the operational meaning of the temperature, in terms of what observers measure, and its relation to the usual Hawking temperature for static black holes. Implications for the final fate of an evaporating black hole are discussed.
Quantum production of black holes at colliders
NASA Astrophysics Data System (ADS)
Arsene, Nicusor; Casadio, Roberto; Micu, Octavian
2016-07-01
We investigate black hole production in p p collisions at the Large Hadron Collider by employing the horizon quantum mechanics for models of gravity with extra spatial dimensions. This approach can be applied to processes around the fundamental gravitational scale and naturally yields a suppression below the fundamental gravitational scale and for increasing number of extra dimensions. The results of numerical simulations performed with the black hole event generator BLACKMAX are here reported in order to illustrate the main differences in the numbers of expected black hole events and mass distributions.